1.by: The blind men thought they could learn what the elephant looked like by

　　 touching it./ make a living by teaching/ by hand手工地，靠手工地，by letter,

　　 by post, by electricity, learn sth. by heart, struck by the beauty因美丽　　　　　

　　 而着迷　 He was paid by the hour/ the day/ month/…他按时/日/月/…被付给工钱。

　　 by plane/ train/ ship/ air/ water/ sea/…,　 by means of用…手段，方式；by

　　 way of经由，取道于…　 learn English by/ over/ through/ on the radio

　　 in the mud在泥中，beyond hope绝望, in freezing在严寒天气中，in danger在危

　　 险中，in trouble在困境中，in public在公共场合中，under construction在建设

　　 中，on business出差，in the same boat处境一样，on sale在出售

4．during是介词，不能引导从句。

3．up to now＝until now, from morning till night, for the time being暂时，

　　 at times有时，day by day一天天地，in no time立刻。

2．on Christmas Day在圣诞节；at Christmas在圣诞节的几天中

1．in+一段时间＝in+一段时间¢s time(与将来时连用)

　　　　　　　　　　 in three days¢ time

　　　　 within+一段时间(用于各种时态)

　　 如：You must finish reading the book within a week.你必须在一周内读完这本书。