1.Three years later,the company suffered the worst loss,____16 percent of its workfforce.A.laid off B.laying off (A与B的区别?)2.What do you think of the people dressed in white?______.A.fascinating B.fanscinated3.It is not_____the group birds leave the nest_____the parent birds will go to the separate ways.A.before when B,after before C,when as D,until that4.Nowhere _____ a greater impression than in pairs.A.he made B.he did make C.did he make D.did he ma

1.B
非谓语动词做状语,一般是考查该动词和句子主语的关系.动词短语lay off(解雇) 这个动作是主语the company主动发出的,就用现在分词.如果以后出现什么“主语被怎样怎样”,即主语与该动词是被动关系,则动词选用过去分词.
写个例子你体会一下：
Seen from the sky,the city is very beautiful.城市被从天上看
Seeing from the sky,he found the city was very beautiful.他从天上看（城市）
2.A
A.fascinating 令人感到着迷的（Ving）
B.fanscinated （自己）感到着迷的(Vpp)
那些人(the people)当然是“令人感到着迷的”,这个人就包括上句的you啊.
类似的有interesting/interested,exciting/excited.
如：I'm (interested) in this (interesting) book.
我对这本令人感到有意思的书感到很有意思
这种题目你只要把中文意思弄清楚明确,就很容易.
3.D
这是not...until...句型的强调句型.
正常句子：The parent birds will not go to the separate ways until the group birds leave the nest.
翻译：直到雏鸟离开鸟窝,它的爸妈才会各奔东西.
不知道楼主对强调句型了解多少.not...until..的强调句型是对until引导的状语进行强调,其结构是：
It is/was not until+状语（从句）+that+主/大句的肯定句.
如：I won't leave until he comes here.
=It is not until the comes here that I will leave.
She didn't leave until 11:00 last night.
=It was not until 11:00 last night that she left.
4.C
这是一个倒装句型,正常句子是：
He made a great impression nowhere than in Paris.
既然把did提前了,当然后面的动词就用原形,而不可能重复出现两个过去时.
想想初中学过的一般疑问句吧：
What did you say at the meeting?
过去式did已经提前,say就只能用原形了.
再如：Why does he like English?
三单3形式does已经在前,后面like也只能用原形了.