中考英语知识点：原因状语从句
(1)原因状语从句通常由because,since,as引导。例如：
Hedidn’tcometoschoolbecausehewasill.
Asitisraining,weshallnotgothezoo.
Sinceyoucan’tanswerthequestion,I’llasksomeoneelse.
(2)because表示直接原因，语气最强。Because引导的原因状语从句多放在主句之后。回答由why提出的问题，只能用because。As和since语气较弱，一般用来表示明显的原因。由as和since引导的原因状语从居多放在句首。例如：
------Whyaren’tgoingthere?
------BecauseIdon’twantto.
Ashehasnocar,hecan’tgetthereeasily.
Sincewehavenomoney,wecan’tbuyit.
(3)because和so不能同用在一个句子里。
[Practice]
1.IkeepanEnglishdiary（）ithelpsmeimprovemywritingskill.
A.howB.when
C.becauseD.if
2.（）hislegwashurt,（）hewalkedslowly.
A.Because;soB.Because;/
C.Although;butD.Although;/
3..Icollecttoysbecausetheyarebeautiful.(对画线部分提问)
（）youcollecttoys?