先做一道题：
On a rainy day I was driving north through Bermont __________ Inotice a young man holding up a sign reading “Boston”.(2000研究生入学考试真题)
[A] which [B] where
[C] when [D] that
【答案】 C
【题意】 在一个下雨天，我开车向北穿过佛蒙特州，此时我注意到一个年轻人举着一
个牌子，上面写着“Boston”。
when 除了引导状语从句外，还可引导并列分句，相当于and then，and at themoment（就在这个时候），表示前面主句句谓语动词动作发生时，另一动作突然发生。
这一用法有一显著特点，主句中谓语部分通常是进行时态或 be about to do sth. 。
1）I was working in the garden when I suddenlyn felt a sharp pain inthe
abdomen.
我正在花院里干活，这时我突然感到一阵腹部肚子剧痛。
2）I was sitting quietly reading when all of a sudden a stone camethurling
throught the window.
我正在坐着静静地看书，冷不防一块石头打窗户飞了进来。
3）I was walking along the river when I heard a drowning boy crying for help.
我正沿着河边散步时，突然听到一个溺水的男孩喊救命声。
4）He was writing the report in the study when I heard my namecalled outside
the window.
他正在书房写报告，突然听到有人在窗外叫他。
5）I was about to leave the house when a postman came, sending me anungent
telegram.
我正要离开家，这时一名邮差給我送来一份加急电报。
6）He was about to give up when he suddenly found the answer.
他正想放弃，这时突然找到了答案。
7）He was just about to dive when he saw the shark.
他正要潜水，突然看到了鲨鱼。
8）We were about to start when it began to rain.
我们刚要出发天开始下起雨来。
● 有时主句中也可用 be on the point of 等表示“正在……”的短语。
1）He was on the point of leaving when someone knocked at thedoor.
他刚要走就有人敲门。
2）One day Chuck was on a flight across the Pacific Ocean whensuddenly his
plane crashed. Chuck survived the crash and landed on a desertedisland.
一天查克开飞机正飞越太平洋，突然飞机失事。查克幸免于难，落到了在一个荒岛上。
发送
先做一道题：
On a rainy day I was driving north through Bermont __________ Inotice a young man holding up a sign reading “Boston”.(2000研究生入学考试真题)
[A] which [B] where
[C] when [D] that
【答案】 C
【题意】 在一个下雨天，我开车向北穿过佛蒙特州，此时我注意到一个年轻人举着一
个牌子，上面写着“Boston”。
when 除了引导状语从句外，还可引导并列分句，相当于and then，and at themoment（就在这个时候），表示前面主句句谓语动词动作发生时，另一动作突然发生。
这一用法有一显著特点，主句中谓语部分通常是进行时态或 be about to do sth. 。
1）I was working in the garden when I suddenlyn felt a sharp pain inthe
abdomen.
我正在花院里干活，这时我突然感到一阵腹部肚子剧痛。
2）I was sitting quietly reading when all of a sudden a stone camethurling
throught the window.
我正在坐着静静地看书，冷不防一块石头打窗户飞了进来。
3）I was walking along the river when I heard a drowning boy crying for help.
我正沿着河边散步时，突然听到一个溺水的男孩喊救命声。
4）He was writing the report in the study when I heard my namecalled outside
the window.
他正在书房写报告，突然听到有人在窗外叫他。
5）I was about to leave the house when a postman came, sending me anungent
telegram.
我正要离开家，这时一名邮差給我送来一份加急电报。
6）He was about to give up when he suddenly found the answer.
他正想放弃，这时突然找到了答案。
7）He was just about to dive when he saw the shark.
他正要潜水，突然看到了鲨鱼。
8）We were about to start when it began to rain.
我们刚要出发天开始下起雨来。
● 有时主句中也可用 be on the point of 等表示“正在……”的短语。
1）He was on the point of leaving when someone knocked at thedoor.
他刚要走就有人敲门。
2）One day Chuck was on a flight across the Pacific Ocean whensuddenly his
plane crashed. Chuck survived the crash and landed on a desertedisland.
一天查克开飞机正飞越太平洋，突然飞机失事。查克幸免于难，落到了在一个荒岛上。
发送