英语:Unit6 lesson4 Dream houses-grammar学案(北师大版必修2)
英语:Unit6 lesson4 Dream houses-grammar学案(北师大版必修2)第3页

(六)as,which引导的非限定性定语从句 

由as, which 引导的非限定性定语从句,as和which可代整个主句,相当于and this或and that。As一般放在句首,which在句中。 

1)As we know, smoking is harmful to one's health. 

2)The sun heats the earth, which is very important to us.