Question

高一英文定语从句（ ）He is absent,_______is often the case.A.what B.wh

Answer 1

as和which都可用来引导非限制性定语从句,来指代整个主句的内容.非限制性定语从句位于句末且as或which在从句中作主语,宾语或表语时,两者常可互换.例如:
He failed in the exam,which/as was natural.
他考试没及格,这很自然.(作主语)
He is an honest boy,which/as anybody can see.
任何人都能看得出来,他是个诚实的孩子.(作宾语)
The man seemed a German,which/as in fact he was.
那个人似乎是个德国人,事实上他就是德国人.(作表语)
但要注意以下区别:
①如果非限制性定语从句位于主句之前或插在主句之中时,只能用as.例如:
As we have seen,oceans cover more than 70 percent of the earth.
我们已经看到,海洋占地球面积的百分之七十多.
This kind of puter,as is well-known,is out of date.
众所周知,这种计算机现在已经过时了.
②as在从句中作主语,后面常跟行为动词的被动式;which在从句中作主语,后常跟行为动词的主动式.例如:
She has been late again,as was expected.
她又迟到了,这是预料之中的.
It rained hard yesterday,which prevented me from going to the park.
昨天雨下得很大,使我无法去公园.
③当从句和主句语意一致时用as,表“正如”;反之用which.例如:
The thief came again,as was expected.
小偷又一次来了,这是预料之中的.(语意一致)
The elephant is like a snake,which is not right.
大象像一条蛇,这是不对的.(语意不一致)
④as常用在 as often happens,as was pointed out,as was said above,as I remember,as I understand等结构中.例如:
Jack has won the first prize,as often happens.
像往常一样,杰克获得了一等奖.