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after与behind的用法辨析
两者均可表示“在…之后”,其区别是：
1.after 主要用于时间或次序,behind 主要用于位置：
He decided to leave after lunch.他决定午饭后离开.
Summer comes after spring.春去夏来.
The hospital is behind the post office.医院在邮局后面.
【注】behind 有时也用于时间,表示“迟于”,主要用于behind time(迟,晚)这一习语：
The train was 20 minutes behind time.火车晚点 20 分钟.
2.两者都可用于引申义,after 侧重指追求、寻找、模仿等；而behind 则侧重指在背后、支持、落后等：
The police are after her.警察在追捕她.
Many young people are after her.许多年青人都追求她.
We are behind you completely.我们完全支持你.
He is behind the others in maths.他的数学不如别人.
after与in的区别
两均可与一段时间连用,表示“在…之后”,但 after 表示以过去时间为起点的一段时间以后,因此通常与过去时连用；而 in 则表示从现在算起的一段时间以后,因此通常用于将来时或含有将来意义的句子：
He came back after three days.3天后他回来了.
I’ll come back in three days.我3天后回来.
I think he can come back in three days.我想他3天后可以回来.
【注】after 除与时间段连用外,还可与时间点连用,此时则可用于将来时(但是in不能与时间点连用)：
He will arrive after five o’clock.他 5 点钟以后到.
另外,after可以与某些表示活动的名词连用,表示“在…之后”(in不能这样用)：after school 放学后 after class 下课后
after the meeting 散会后 after liberation 解放后
hair还是hairs?
先来看一道题：
a.He must be very old.Look,he has grey ________.
b.He found some ________ in his soup.
A.hair,hair B.hairs,hairs C.hair,hairs D.hairs,hair
【分析】此题应选 C,容易误选 A,误认为hair永远不可数.其实hair这个词既可以是可数的,也可以是不可数,只是含义稍有变化：
1.作为可数名词,是指一根一根的“头发”或“毛发”：
Look at this,a hair in my soup.你瞧,我的汤里有根头发.
The cat has left her loose hairs all over my clothes.猫掉的毛弄得我衣服上到处都是.
My father has quite a few gray hairs.我父亲已有不少白发.
There is not a gray hair on his head.他头上没有一根白头发.
2.作为不可数名词“头发”的总称,是集合名词：
I'll have my hair cut.我要去理发.
He has blond hair.他有一头金发.
She has a beautiful head of hair.她有一头漂亮的头发.
The woman likes to do her hair in foreign style.这个女人喜欢把头发梳成外国式.
试比较以下句子：
He has grey hair.他满头白发.
He has grey hairs.他有些白发了.
after与behind的用法辨析
两者均可表示“在…之后”,其区别是：
1.after 主要用于时间或次序,behind 主要用于位置：
He decided to leave after lunch.他决定午饭后离开.
Summer comes after spring.春去夏来.
The hospital is behind the post office.医院在邮局后面.
【注】behind 有时也用于时间,表示“迟于”,主要用于behind time(迟,晚)这一习语：
The train was 20 minutes behind time.火车晚点 20 分钟.
2.两者都可用于引申义,after 侧重指追求、寻找、模仿等；而behind 则侧重指在背后、支持、落后等：
The police are after her.警察在追捕她.
Many young people are after her.许多年青人都追求她.
We are behind you completely.我们完全支持你.
He is behind the others in maths.他的数学不如别人.
after与in的区别
两均可与一段时间连用,表示“在…之后”,但 after 表示以过去时间为起点的一段时间以后,因此通常与过去时连用；而 in 则表示从现在算起的一段时间以后,因此通常用于将来时或含有将来意义的句子：
He came back after three days.3天后他回来了.
I’ll come back in three days.我3天后回来.
I think he can come back in three days.我想他3天后可以回来.
【注】after 除与时间段连用外,还可与时间点连用,此时则可用于将来时(但是in不能与时间点连用)：
He will arrive after five o’clock.他 5 点钟以后到.
另外,after可以与某些表示活动的名词连用,表示“在…之后”(in不能这样用)：after school 放学后 after class 下课后
after the meeting 散会后 after liberation 解放后
hair还是hairs?
先来看一道题：
a.He must be very old.Look,he has grey ________.
b.He found some ________ in his soup.
A.hair,hair B.hairs,hairs C.hair,hairs D.hairs,hair
【分析】此题应选 C,容易误选 A,误认为hair永远不可数.其实hair这个词既可以是可数的,也可以是不可数,只是含义稍有变化：
1.作为可数名词,是指一根一根的“头发”或“毛发”：
Look at this,a hair in my soup.你瞧,我的汤里有根头发.
The cat has left her loose hairs all over my clothes.猫掉的毛弄得我衣服上到处都是.
My father has quite a few gray hairs.我父亲已有不少白发.
There is not a gray hair on his head.他头上没有一根白头发.
2.作为不可数名词“头发”的总称,是集合名词：
I'll have my hair cut.我要去理发.
He has blond hair.他有一头金发.
She has a beautiful head of hair.她有一头漂亮的头发.
The woman likes to do her hair in foreign style.这个女人喜欢把头发梳成外国式.
试比较以下句子：
He has grey hair.他满头白发.
He has grey hairs.他有些白发了.