1.on pins and needles:就是像坐在大头针和缝衣针上面一样的感觉，所以叫如坐针毡。
用法:I was on pins and needles until I knew my marks.在知道成绩之前我如坐针毡。

14'

26'

2.whet sb.'s appetite:掉起某人的胃口，引起某人的兴趣.
用法:He whetted her appetite to stay in the company by supplying high salary.

17'

3.in need:需要帮助的
用法:A friend in need is a friend indeed.患难见真情。

17'

35'