Unit6 Space exploration-grammar學案
unit6 space exploration-grammar學案條件狀語從句
在復合句中，由從句表示的狀語叫做狀語從句。它可以用來修飾主語中的動詞.形容詞.副詞等。根據(jù)它表達的意思，狀語從句可以分為時間狀語從句，地點狀語從句，條件狀語從句，比較狀語從句，目的狀語從句，結(jié)果狀語從句和讓步狀語從句等。由連接詞if或unless引導的狀語從句叫做條件狀語從句。（注意：在含有條件狀語從句的復合句中，如果主句是一般將來時態(tài)，從句要用一般現(xiàn)在時[主將從現(xiàn)原則])
經(jīng)典語句：if it doesn't rain tomorrow, we will go to the zoo.
if you open the door，i will come in.
條件狀語從句就是用以表示“在某種條件下,會……”。常用if ,in case , on condition等詞來引導，連接詞主要有 if, unless, as/so long as, on condition that, provided, suppose, supposing 等。主句用一般將來時，if或unless引導的條件狀語從句用一般現(xiàn)在時。
固定搭配：unless = if...not.
e.g. let's go out for a walk unless you are too tired.
if you are not too tired, let's go out for a walk.
if 引導的條件句有真實條件句和非真實條件句兩種:
真實條件句，
如：if it rains tomorrow, we won’t go on a picnic.
非真實條件句是虛擬語氣的一種，表示與事實相反，如：
if i were you, i would go with him.
so/as long as只要
由as (so) long as, in case引導。
so long as you’re happy, it doesn’t matter what you do.
只要你高興，你做什么都沒有關(guān)系。
you may borrow my book as long as you keep it clean.
只要你保持書的清潔，你就可以把我的書借去。
take your umbrella in case it rains.
帶著你的傘吧，以防下雨。
【練一練】
用括號內(nèi)所給動詞的適當形式填空。
1. if you (get) up early tomorrow morning, you (catch) the early bus.
2. if he (be) free this weekend, he (visit) his grandparents.
3. —i don’t know if he (come) to the party.
—don’t worry. if he (come), i will let you know first.
4. (leave) it for me if mary (not want) to do it.
keys:
1. get; will catch 2. is; will visit
3. will come; comes 4. leave; doesn’t want