從屬連詞when/after/before在引導(dǎo)狀語從句時應(yīng)該怎么用?

when before after 從屬連詞定義

用來連接兩個子句：引導(dǎo)狀語從句，連接主句。

狀語從句必須依附主句，不能單獨存在。

狀語從句在前，主句在后，兩個句子中間必須加上逗號。

When 用法（當(dāng)...的時候）

主句+when+狀語從句 = When+狀語從句，主句

When she has money, she likes to buy books.

當(dāng)她有錢的時候，她喜歡買書。

I said hi to him when I saw him.

= When I saw him, I said hi to him.

當(dāng)我看見他的時候，我對他說了聲嗨。

表示現(xiàn)在的習(xí)慣或狀態(tài)

主句(現(xiàn)在式)+ when + 狀語從句(現(xiàn)在式)

Peter likes to go jogging when he is free.

當(dāng)Peter有空的時候，他喜歡去慢跑。

表示未來會發(fā)生的事

主句(未來式/祈使句)+ when +狀語從句(現(xiàn)在式)

I will give you a gift when you come here tomorrow.

當(dāng)你明天來的時候，我將會給你一個禮物。

Be careful when you walk on the street at night.

當(dāng)你夜晚走在街頭的時候，要小心。

表示過去發(fā)生的事情

主句(過去式)+ when + 狀語從句(過去式)

Sam went outside when he heard Tina screaming.

當(dāng)Sam聽到Tina尖叫時，他跑到外面去。

My mom was cooking dinner when Vivian rang the doorbell.

當(dāng)Vivian按門鈴時，我媽媽在煮晚餐。

after（在.…..之后）/ before（在.…..之前）用法

主句+after/before+狀語從句

= After/Before+狀語從句，主句

After he eats breakfast, he goes to work.

在他吃早餐之后，他去上班。

表示現(xiàn)在的習(xí)慣或狀態(tài)

主句(現(xiàn)在式)+ after/before + 狀語從句(現(xiàn)在式)

He watches TV after he finishes his work every night.

= After he finishes his work every night, he watches TV.

每天晚上，在他完成工作之后，他會看電視。

She brushes her teeth before she goes to bed.

= Before she goes to bed, she brushes her teeth.

她在上床睡覺之前會刷牙。

表示未來會發(fā)生的事

主句(未來式/祈使句)+ after/before +狀語從句(現(xiàn)在式)

I will give you a gift after you come here tomorrow.

在你明天來后，我將會給你一個禮物。

Before you have dinner, wash your hands.

在你吃晚餐前，先洗洗手。

表示過去發(fā)生的事

主句(過去式)+ after/before +狀語從句(過去式)

Tony had a big dinner with his family before he went to England.

=Before Tony went to England, he had a big dinner with his family.

在Tony去英國之前，他和他的家人吃了頓大餐。

Before和After當(dāng)介詞用法

Before/After后面接名詞

He studies very hard before the test this time.

這次考試之前，他非常認(rèn)真念書。

He bought many snacks before the field trip.

遠(yuǎn)足前，他買了很多零嘴。

When/Before/After后面接動名詞

Before和After所引導(dǎo)從句，如果主語與主句相同時，去除從句的主語并將動詞改為動名詞。

After she ate dinner, she watched TV.

= After eating dinner, she watched TV.

吃完晚餐后，她看電視。

After she played the violin, she played basketball.

= After playing the violin, she played basketball.

彈完小提琴后，她打籃球。

Before she took the tests, she studied hard.

= Before taking the tests, she studied hard.

參加考試前，她用功念書。

Before you cook the vegetables, you must wash them.

= Before cooking the vegetables, you must wash them.

在烹煮蔬菜前，你必須先洗一洗。

When I watch TV, I usually have some popcorn.

= When watching TV, I usually have some popcorn.

當(dāng)看電視時，我常常吃爆米花。

When I do the sports, I like to wear sneakers.

= When doing the sports, I like to wear sneakers.

當(dāng)運動時，我喜歡穿運動鞋。

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