1.The firemen have been examining the ground _______yesterda
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