The manager told us to be friendly to the visitors as if we _____( meet) them before.

　　had met

　　If only we ______(have) a phone! I'm tired of waiting outside the public phone box.

　　D.in case ， for fear that ， lest 等詞后從句的謂語動詞為(should) + 原形。

　　He took his umbrella with him lest it _______ (rain.)

　　(should) rain

　　E.在It is (high) time that 從句中謂語動詞一般用過去時動詞。

　　It's high time that we _______(take) firm measures to protect our environment. took

　　F.時間錯綜條件句，動詞的形式要根據表示的時間調整。

　　如果我們早動身，現在就不會在雨中走了。

　　If we had set out earlier,we wouldn't be walking in the rain.

　　(從句中動作發生在過去，主句中動作發生在現在。)

　　4)動詞的非謂語動詞形式：

　　A.動詞不定式：主要考查動詞不定式作定語、賓語、賓語或主語補足語等的用法。還要注意動詞不定式的被動式與完成式。

　　不定式作定語：If there is no choice,there is no decision ______(make) to be made

　　不定式作賓語： Robots , already taking over human tasks in the automotive field, are beginning ________(see) . to be seen