1.bit of (a little= a bit of)
2.so that (in order to 为目的状语结构,可与so that+句子互换)
3.At last (eventually = at last/ finally)
4.How did (这个句子意为“他们一个接着一个从狭窄的空缺里跳出来”故询问one at a time应问“他们是怎么跳出来的”,故应该问how did)
5.so as (in order to =so as to,都表目的加动词原形)
6.been away (现在完成时加一段时间for three year,句子应该用延续动词.“她已经离开上海三年了.”就应该使用be动词been away)