组成句子的各个组成部分叫句子成分： 主 谓 宾 定 状 补 表1. 主语:通常由名词,代词,动词不定式,动名词, 从句来充当. ( climb ) the mountains was hard but as we looked around us, we were surprised by the view. is necessary tomasteraforeignlanguage. To climb/ climbing It2.谓语:通常由动词充当. 1.They work very hard. 2.Tom feels much better now. 情态动词和助动词不能单独充当谓语,必须 和实义动词或系动词一起构成复合谓语. They can speak English well. They are playing over there. We are students. 动词常分为实义动词,系动词,情态动词和助动词.3. 表语：跟在系动词后面的词语或从句, 用来说明主语的身份,特征,状态. The truth is that he has never been abroad.
