1.who
who在定语从句中担任主语,其先行词必须是表示人的名词或代词.who也可以代替在从句中担任宾语的whom,但是它前面不能有介词.
Ihaveafriendwholikeslisteningtoclassicalmusic.(who在从句中作主语,代替前面的afriend)
LuckilynoneofthepeoplewhoIknowwerekilledintheearthquake.(who在从句中作宾语,代替前面的thepeople)
2.which
which所代替的先行词是表示事物或动物的名词或代词,一般不用来指人.
①which在从句中作主语或宾语.
Shewasnotonthetrainwhicharrivedjustnow.(which在从句中作主语,代替先行词thetrain)
Thewatch(which)yougavemekeepsgoodtime.(which在从句中作宾语,代替先行词thewatch,可省略)
②which引导的定语从句可表示一个概念.
which的先行词有时不是一个词,而是主句所表示的整个现象,此时,which前一定要使用逗号.
Jamesdidreallywellinhisexams,whichwasabigsurprise.(which相当于andthat,其先行词是前面整个句子)
HehastohavelessonsonSundays,whichhedoesn'tlikeatall.
③which在从句中作定语.
which在定语从句中有时也能作定语.这种用法比较正式,经常出现在书面语中.
TheBeijingOlympicGamesarebeingheldinthreeyears,bywhichtimeIwillbe21.
Itmightsnowthisweekend,inwhichcasewewon'tgohikinginthemountains.