Python の open() でファイルを読み込む際の Unicode エンコーディングの問題

Python reads a file
f = open('D:/python/cpwords.txt','r',encoding='utf-8')
print(*f)

f = open('D:/Workspaces/python/cpstopwords.txt','r',encoding='utf-16')
print(*f)

Help on built-in function open in module io:

open(file, mode='r', buffering=-1, encoding=None, errors=None, newline=None, closefd=True, opener=None)
    Open file and return a stream. Raise IOError upon failure.
    
    file is either a text or byte string giving the name (and the path
    if the file isn't in the current working directory) of the file to
    file is either a text or byte string giving the name (and the path if the file isn't in the current working directory) of the file to be opened or an integer file descriptor of the file to be
    (If a file descriptor is given, it is closed when the
    (If a file descriptor is given, it is closed when the returned I/O object is closed, unless closefd is set to False.)
    
    mode is an optional string that specifies the mode in which the file
    It defaults to 'r' which means open for reading in text
    Other common values are 'w' for writing (truncating the file if
    it already exists), 'x' for creating and writing to a new file, and
    'a' for appending (which on some Unix systems, means that all writes
    append to the end of the file regardless of the current seek position).
    In text mode, if encoding is not specified the encoding used is platform
    dependent: locale.getpreferredencoding(False) is called to get the
    (For reading and writing raw bytes use binary
    mode and leave encoding unspecified.) The available modes are:
    
    ========= ===============================================================
    Character Meaning
    --------- ---------------------------------------------------------------
    'r' open for reading (default)
    'w' open for writing, truncating the file first
    'x' create a new file and open it for writing
    'a' open for writing, appending to the end of the file if it exists
    'b' binary mode
    't' text mode (default)
    '+' open a disk file for updating (reading and writing)
    'U' universal newline mode (deprecated)
    ========= ===============================================================
    
    The default mode is 'rt' (open for reading text). For binary random
    access, the mode 'w+b' opens and truncates the file to 0 bytes, while
    For binary random access, the mode 'w+b' opens and truncates the file to 0 bytes, while 'r+b' opens the file without truncation.
    raises an `FileExistsError` if the file already exists.
    
    Python distinguishes between files opened in binary and text modes,
    Files opened in
    binary mode (appending 'b' to the mode argument) return contents as
    In text mode (the default, or when
    't' is appended to the mode argument), the contents of the file are
    returned as strings, the bytes having been first decoded using a
    platform-dependent encoding or using the specified encoding if given.
    
    'U' mode is deprecated and will raise an exception in future versions
    It has no effect in Python 3. Use newline to control
    universal newlines mode.
    
    buffering is an optional integer used to set the buffering policy.
    Pass 0 to switch buffering off (only allowed in binary mode), 1 to select
    line buffering (only usable in text mode), and an integer > 1 to indicate
    When no buffering argument is given, the default buffering policy is
    When no buffering argument is given, the default buffering policy works as follows:
    
    * Binary files are buffered in fixed-size chunks; the size of the buffer
      is chosen using a heuristic trying to determine the underlying device's
      "block size" and falling back on `io.DEFAULT_BUFFER_SIZE`.
      On many systems, the buffer will typically be 4096 or 8192 bytes long.
    
    On many systems, the buffer will typically be 4096 or 8192 bytes long. * "Interactive" text files (files for which isatty() returns True)
      Other text files use the policy described above
      for binary files.
    
    encoding is the name of the encoding used to decode or encode the
    This should only be used in text mode. The default encoding is
    platform dependent, but any encoding supported by Python can be
    See the codecs module for the list of supported encodings.
    
    errors is an optional string that specifies how encoding errors are to
    errors is an optional string that specifies how encoding errors are to be handled---this argument should not be used in binary mode.
    'strict' to raise a ValueError exception if there is an encoding error
    (the default of None has the same effect), or pass 'ignore' to ignore
    errors. (Note that ignoring encoding errors can lead to data loss.)
    See the documentation for codecs.register or run 'help(codecs.Codec)'
    for a list of the permitted encoding error strings.
    
    newline controls how universal newlines works (it only applies to text
    mode). It can be None, '', '\n', '\r', and '\r\n'.  It works as
    It works as follows:
    
    * On input, if newline is None, universal newlines mode is enabled.
      Lines in the input can end in '\n', '\r', or '\r\n', and
      these are translated into '\n' before being returned to the
      If it is '', universal newline mode is enabled, but line
      If it has any of
      If it has any of the other legal values, input lines are only terminated by the given
      If it has any of the other legal values, input lines are only terminated by the given string, and the line ending is returned to the caller untranslated.
    
    * On output, if newline is None, any '\n' characters written are
      On output, if newline is None, any '\n' characters written are translated to the system default line separator, os.linesep.
      If newline is '' or '\n', no translation takes place.
      If newline is '' or '\n', no translation takes place.
      to the

Help on built-in function open in module io:

open(file, mode='r', buffering=-1, encoding=None, errors=None, newline=None, closefd=True, opener=None)
    Open file and return a stream. Raise IOError upon failure.
    
    file is either a text or byte string giving the name (and the path
    if the file isn't in the current working directory) of the file to
    file is either a text or byte string giving the name (and the path if the file isn't in the current working directory) of the file to be opened or an integer file descriptor of the file to be
    (If a file descriptor is given, it is closed when the
    (If a file descriptor is given, it is closed when the returned I/O object is closed, unless closefd is set to False.)
    
    mode is an optional string that specifies the mode in which the file
    It defaults to 'r' which means open for reading in text
    Other common values are 'w' for writing (truncating the file if
    it already exists), 'x' for creating and writing to a new file, and
    'a' for appending (which on some Unix systems, means that all writes
    append to the end of the file regardless of the current seek position).
    In text mode, if encoding is not specified the encoding used is platform
    dependent: locale.getpreferredencoding(False) is called to get the
    (For reading and writing raw bytes use binary
    mode and leave encoding unspecified.) The available modes are:
    
    ========= ===============================================================
    Character Meaning
    --------- ---------------------------------------------------------------
    'r' open for reading (default)
    'w' open for writing, truncating the file first
    'x' create a new file and open it for writing
    'a' open for writing, appending to the end of the file if it exists
    'b' binary mode
    't' text mode (default)
    '+' open a disk file for updating (reading and writing)
    'U' universal newline mode (deprecated)
    ========= ===============================================================
    
    The default mode is 'rt' (open for reading text). For binary random
    access, the mode 'w+b' opens and truncates the file to 0 bytes, while
    For binary random access, the mode 'w+b' opens and truncates the file to 0 bytes, while 'r+b' opens the file without truncation.
    raises an `FileExistsError` if the file already exists.
    
    Python distinguishes between files opened in binary and text modes,
    Files opened in
    binary mode (appending 'b' to the mode argument) return contents as
    In text mode (the default, or when
    't' is appended to the mode argument), the contents of the file are
    returned as strings, the bytes having been first decoded using a
    platform-dependent encoding or using the specified encoding if given.
    
    'U' mode is deprecated and will raise an exception in future versions
    It has no effect in Python 3. Use newline to control
    universal newlines mode.
    
    buffering is an optional integer used to set the buffering policy.
    Pass 0 to switch buffering off (only allowed in binary mode), 1 to select
    line buffering (only usable in text mode), and an integer > 1 to indicate
    When no buffering argument is given, the default buffering policy is
    When no buffering argument is given, the default buffering policy works as follows:
    
    * Binary files are buffered in fixed-size chunks; the size of the buffer
      is chosen using a heuristic trying to determine the underlying device's
      "block size" and falling back on `io.DEFAULT_BUFFER_SIZE`.
      On many systems, the buffer will typically be 4096 or 8192 bytes long.
    
    On many systems, the buffer will typically be 4096 or 8192 bytes long. * "Interactive" text files (files for which isatty() returns True)
      Other text files use the policy described above
      for binary files.
    
    encoding is the name of the encoding used to decode or encode the
    This should only be used in text mode. The default encoding is
    platform dependent, but any encoding supported by Python can be
    See the codecs module for the list of supported encodings.
    
    errors is an optional string that specifies how encoding errors are to
    errors is an optional string that specifies how encoding errors are to be handled---this argument should not be used in binary mode.
    'strict' to raise a ValueError exception if there is an encoding error
    (the default of None has the same effect), or pass 'ignore' to ignore
    errors. (Note that ignoring encoding errors can lead to data loss.)
    See the documentation for codecs.register or run 'help(codecs.Codec)'
    for a list of the permitted encoding error strings.
    
    newline controls how universal newlines works (it only applies to text
    mode). It can be None, '', '\n', '\r', and '\r\n'.  It works as
    It works as follows:
    
    * On input, if newline is None, universal newlines mode is enabled.
      Lines in the input can end in '\n', '\r', or '\r\n', and
      these are translated into '\n' before being returned to the
      If it is '', universal newline mode is enabled, but line
      If it has any of
      If it has any of the other legal values, input lines are only terminated by the given
      If it has any of the other legal values, input lines are only terminated by the given string, and the line ending is returned to the caller untranslated.
    
    * On output, if newline is None, any '\n' characters written are
      On output, if newline is None, any '\n' characters written are translated to the system default line separator, os.linesep.
      If newline is '' or '\n', no translation takes place.
      If newline is '' or '\n', no translation takes place.
      to the