用介词填空

1 The book is （about ） differences between British English and American English
about:关于(个人人为of也可以,因有be of的用法)

2 Just （at ） that moment he came
at that moment为固定用法:那时

1 The book is （on） differences between British English and American English
on:（文章、论文、书）关于

2 Just （at ） that moment he came
at that moment为固定用法:那时

about 关于
at 在~~时间

1. of be of +名词= 形容词
2. at