初中英語知識點總結(jié)：初中英語語法——從屬連詞用法

　　從結(jié)構(gòu)上說，英語連接詞分兩大類：并列連詞和從屬連詞。

　　并列連詞連接兩個或兩個以上地位平等的字、詞組或分句。例如：

　　(1) Air and water are indispensable to me.

　　(2) She likes going out with friends or playing outdoor games.

　　(3) Most workers have a good income, so they look very happy.

　　從屬連詞連接兩個或兩個以上的分句，形成復(fù)雜句中的從屬分句。例如：

　　(4) He said that he did not want to go .

　　(5) Many things have happened since I last saw him.

　　(6) You may come if you want to.

　　從屬連詞用來連接各種從句。

　　until(till)直到，在用until表達時間狀語的句子中，主句中的動詞是要十分小心去選擇的。

　　如動詞是持續(xù)行動詞，它要用肯定句，如：

　　I studied hard until 12 o'clock last night.

　　如果動詞是瞬間截止性動詞，則要用否定句，如:

　　He didn't go to bed until his mother came back.

　　由since,for,by,before, 來引導(dǎo)的時間狀語從句。

　　since 引導(dǎo)的時間狀語是動作的開始時間，如:

　　I have studied English since 1990.

　　而by引導(dǎo)的時間狀語通常是動作的結(jié)束時間，如：

　　I had learned 25 English songs by the end of last term.