謂語動詞是組成句子的其中之一主幹，要通過句子的結構來判斷句子是否缺謂語
非謂語動詞一般是作賓語和狀語，作賓語的話要看看前面那個動詞的搭配，例如，decide後面一般是decide to do sth， enjoy doing sth， finish doing sth等等。
判斷時態可以通過句子的時間狀語或者上下文所提示的時間狀語來判斷
動詞不定式
1．常用形式：一般主動式to do， 一般被動式to be done
完成主動式to have done， 完成被動式to have been done
進行式to be doing
2．語法功能：可作主語、表語、賓語、賓補、定語和狀語（即除謂語之外的各種成
分）。例如：
1）主語：To master a foreign language is very important.
2）表語：My job is to drive them to the company every day.
3）賓語：Do you want to visit the Great Wall?
Can you give us some advice on what to do next?
賓補：The teacher advised us to have a rest first.
I didn´t notice them come in.
注：see， hear， watch， notice， have， make， let等動詞後作賓補的動詞不定式不帶to， 但變為被動語態以後（即不定式作主補時）要帶to， （其中let sb. do sth. 變為被動式為sb. is let do sth.）
help（幫助）後作賓補的動詞不定式可帶to，也可不帶to. 即help sb.(to)do sth.
定語：不定式位於所修飾的名詞，代詞之後，如：Who was the first one to set
to the top of the hill yesterday? /He is the man to depend on/to believe in.
6）狀語： in order to
A．目的狀語：She reads China Daily every day so as to improve her English.
to
注：in order to 可以位於句首或句中，so as to 不能位於句首。
B．原因狀語： I’m glad to see you . 注：這種“be＋形容詞＋不定式”結構，其不定式有時也可視為賓語，如：He is eager to go to college./ She is sure to come here.
C．結果狀語：They lived to see the liberation of their home town.他們一直活到見到家鄉解放。
品位站
