這個問題屬于非謂語動詞的用法。非謂語動詞主要是三種形式：第一，動詞不定式即to do形式，表達(dá)要做的事，比如To go a college is my dream.再比如We need to find a place to eat something;第二是動名詞即v-ing形式，表達(dá)正在進(jìn)行或伴隨性狀態(tài)卻不是進(jìn)行時態(tài)，因?yàn)檫M(jìn)行時態(tài)動名詞前要加be動詞.比如He went to bed listening to the music last night.再比如She sat in the classroom lisenting to the teacher;第三是過去分詞作定語，表達(dá)被動的意思，卻不是被動語態(tài)，因?yàn)楸粍诱Z態(tài)的過去分詞前要加be動詞，比如a boy called Tom,一個被叫做湯姆的男孩，a book written by Luxun一本被魯迅寫的書。