當(dāng)關(guān)系代詞指代整個句子時都是非限制性定語從句,定語從句前要加逗號,關(guān)系代詞不能用that,表示“事”或“物”只能用which,as,表示“人”只能用who,whom.用在句首時只能用as.
He seems not to have grasped what I meant,which greatly upsets me.
他似乎沒抓住我的意思,這使我心煩.
Liquid water changes to vapor,which is called evaporation.
液態(tài)水變?yōu)檎羝?這就叫做蒸發(fā).
As is known to everybody,the moon travels round the earth once every month．
這如大家知道的那樣,月亮每個月圍繞地球運轉(zhuǎn)一周.（as 引導(dǎo)的就是置于句首的非限制性定語從句,修飾后面的整個句子.）
以上這三個例句中都不能用that來引導(dǎo).