1.表语(一般是形容词,名词,跟在系动词(be)后面） He is tall.(tall---表语) It is water.(water) 2.表语从句(is + that/what/how/when/where 从句）当表语用的句子 The problem is (how/when to get there) 3.宾语从句( do + that/how）充当宾语的句子 I know (that she likes you) 4.同位语从句 （当同位语用的句子） Tom ,(who is the monitor),is very rude.
