误Chinese letters are difficult to learn.
正Chinese characters are difficult to learn.
析letter指“字母”(即a, b, c等26个字母),汉语中的“汉字”要用character来表示。
请函告一些进一步的变化。误Please inform me of any further changes by a letter.
正Please inform me of any further changes by letter.
析在by letter, by air mail, by telegram等短语中,名词前均不用冠词。