介词又叫前置词,是一种虚词。
介词不能单独作句子成分,必须与名词或代词(或相当于名词的其它词类、短语或从句)构成介词短语,才能在句中充当一个成分。介词分为:
1)简单介词。例如:at,in,on,besides,since,for等;
2)合成介词。例如:inside,without等;
3)短语介词。例如:because of,in front of,instead of,in spite of等;
4)二重介词。例如:from behind,until after等。
1.介词短语的作用
1)作定语。例如:
The key to the door is missing.
2)作状语。例如:
The book is very popular with young people.
3)作表语。例如:
Japan is to the east of China.
4)作宾语补足语。例如:
Make yourself at home.
2.注意以下常用介词的区别
1)at,in,on和by表示时间的区别:at指时间表示:
①时间的一点、时刻等。例如:
They come home at sunrise(at noon,at midnight,at ten o'clock,at day-break,at dawn).
②较短暂的一段时间。可指某个节日或被认为是一年中标志大事的日子。例如:
He went home at Chirstmas(at New Year,at the Spring Festival,at night,at midsummer).
At the beginning(middle,end)of that month he was sick.His grandfather died at seventy two.
in指时间表示:
①在某个较长的时间(如世纪、朝代、年、月、季节及泛指的上午、下午和傍晚等)内。例如:
He was born in 1942.
He did it in the holidays.
②在一段时间之后,例如:
I will finish it in three hours.He will come round in a day or two.
注:在表示时间点的名词(词组)前用after。
on指时间表示:
①具体的时日和一个特定的时间,如某日,星期几等。例如:
On May 4th(On Sunday,On New Year's Day,On Christmas Day),there will be a celebration. He will come to meet us on our arrival.
②在某个特定的早晨、下午或晚上。例如:
He died on the eve of victory(胜利前夕).
He arrived at 10 o'clock on the night of the 5th.
③准(时),按(时)。例如:
If the train should be on time,I should reach home before dark.
by指时间表示:
①不迟于,在(某时)前。例如:
He must have returned by
now.Jack had made some friends by the time you came.
He will come by six o'clock.
By then he was more than fifty years of age.
②在……间,在……的时候。例如:
He worked by day and slept by night.
I don't like travelling by night.
2)near,by,beside,at表示"在……附近"的区别:near表示相对的"近",实际距离可能还很远。例如:
Suzhou is near Shanghai.
There is a post office near our school.
by和beside都表示"靠近",实际距离不可能很远,但beside比by更具体地表示出"在……旁边"的意思。例如:
He was sitting beside her.
There is a big tree by the river.
at也有"在旁边"的意思,但多表示有目的的行为所处的位置,而by和be-side仅表示位置关系。例如:
The students are sitting at the desks listening to the teacher.
Several students are sitting by/beside the window talking about a film.
