1.The firemen have been examining the ground _______yesterday.
问题描述：
1.The firemen have been examining the ground _______yesterday.
A.since B.for C.ago D.by
2.They discovered the cause _________.
A.by chance B.chancily C.fortunately D.luckily
3.The bird had snatched up the snake form the ground.It had _____it.
A.taken B.pulled C.seized D.caried
4.She had hardly got backto the kitchen _______ doorbell rang.
A.when B.lthen C.as D.as soon as
答
1 A since,自从,多用于现在完成时
2 A 偶然地,chancily是不安全的,C,D都是幸运地
3 C 抓住
4 A hardly.when,刚一...就.主句使用过去完成时