假如掌握了語法，做起英文練習就快了。下面是小編整理的全國英語等級考試二級語法知識，希望對大家有用，更多訊息請關注應屆畢業生網。
用一般過去時代替完成時
1) 兩個動作如按順序發生，又不強調先後，或用then，and，but 等連詞時，多用一般過去時。
When she saw the mouse，she screamed.
My aunt gave me a hat and I lost it.
2 ) 兩個動作相繼發生，可用一般過去時;如第一個動作需要若干時間完成，用過去完成時。
When I heard the news, I was very excited.
3) 敘述歷史事實，可不用過去完成時，而只用一般過去時。
Our teacher told us that Columbus discovered America in 1492.
過去完成時典型例題
The students ___ busily when Miss Brown went to get a book she ___ in the office.
A. had written, left
B. were writing, has left
C. had written, had left
D. were writing, had left
答案D. "把書忘在辦公室"發生在"去取書"這一過去的動作之前，因此"忘了書"這一動作發生在過去的過去，用過去完成時。句中when表示的是時間的一點，表示在"同學們正忙於……"這一背景下，when所引導的動作發生。因此前一句應用過去進行時。
注意：
had no … when 還沒等…… 就……
had no sooner… than 剛…… 就……
He had no sooner bought the car than he sold it.
過去完成時
1) 概念：
表示過去的'過去
其構成是had +過去分詞構成。
那時以前 那時 現在
2) 用法
a.在told, said, knew, heard, thought等動詞後的賓語從句。
She said (that) she had never been to Paris.
b. 狀語從句
在過去不同時間發生的兩個動作中，發生在先，用過去完成時;發生在後，用一般過去時。
When the police arrived, the thieves had run away.
c. 表示意向的動詞，如hope, wish, expect, think, intend, mean, suppose等，用過去完成時表示"原本…，未能…"
We had hoped that you would come, but you didn't.
3)過去完成時的時間狀語：
before, by, until , when, after, once, as soon as.
He said that he had learned some English before.
By the time he was twelve, Edison had began to make a living by himself.
Tom was disappointed that most of the guests had left.
現在進行時
現在進行時的基本用法：
a. 表示現在( 指說話人說話時) 正在發生的事情。
We are waiting for you.
b. 習慣進行：表示長期的或重複性的動作，說話時動作未必正在進行。
Mr. Green is writing another novel.
(說話時並未在寫，只處於寫作的狀態。)
She is learning piano under Mr. Smith.
c. 表示漸變的動詞有：get, grow, become, turn, run, go, begin等。
The leaves are turning red.
It's getting warmer and warmer.
d. 與always, constantly, forever 等詞連用，表示反覆發生的動作或持續存在的狀態，往往帶有說話人的主觀色彩。
You are always changing your mind.
典型例題
My dictionary ___, I have looked for it everywhere but still___ it.
A. has lost, don't findB. is missing, don't find C. has lost, haven't found D. is missing, haven't found.
答案D. 前句是一個仍在持續的狀態，應用進行時，由於沒有找到，其影響仍然存在，應用完成時，瞬間動詞用於否定式時可用於完成時。
