37. 〔误〕 Till the end of next week. I will have finished this work. 〔正〕 By the end of next week. I will have finished this work. 〔析〕 by 引起的时间状语表示了动作的截止点，其意思为"不迟于某一时刻将工作做完"，所以主句一般是完成时态。当然可以有将来时态，如：Ill be there by five oclock.而till则表达其一动作一直持续到某一时刻，但句中的动词一定要用持续性动词，而瞬间的截止性动词应用其否定句式，如：I wont finish this work till(until) next weekend.
38. 〔误〕 He came to London before last weekend. 〔正〕 He had come to London before last weekend.
〔正〕 He came to London two weeks ago. 〔析〕 before 一般要与完成时连用，而ago则与一般过去时连用。
39. 〔误〕I have studied English for three years gince I had come here.正 I have studied English for three years since I came here. 析 since用来表达主句动作的开始时间，所以其引出的从句中应为过去时，而不能用完成时态
40. 〔误〕 I can help you repair this bike. You will get it after two hours. 〔正〕 I can help you repair this bike. You will get it in two hours. 〔析〕中文经常讲两小时之后来取，两天内会修好，而这个介词在英文中要用in而不要用after。其原因有二，①after 多用于过去时，如：I arrived in New York. After three days, I found a job in the bank. ② after 加时间是表达一个不确定的时间范围，如：after three days, 即三天之后的哪一天都可以。所以在许诺若干时间内会完成某事时，一定要用介词in。
41.误〕 Three days after he died. 正〕 After three days he died. 〔正〕 Three days later he died.
〔析〕 after 与 later都可以用来表达一段时间之后，但它们所处的位置不同，after 在时间词前，而later在时间词后。
42.〔误〕 She hid herself after the tree. 〔正〕 She hid herself behind the tree.
〔析〕 after多用来表达某动作之后，所以有的语法书中称它为动态介词，如：I run after him. After finishing my homework, I went to see a film. 而behind则多用于静态事物之后。
43.〔误〕 There is a beautiful bird on the tree. 正〕 There is a beautiful bird in the tree.
〔析〕 树上长出的果实，树叶要用on, 而其他外来的人、物体均要用in the tree.
44.〔误〕 Shanghai is on the east of China. 〔正〕 Shanghai is in the east of China.
〔析〕 在表达地理位置时有3个介词：in, on, to。 in表示在某范围之内; on表示与某地区接壤;to则表示不相接。如：Japan is to the east of China.
45.〔误〕 I arrived at New York on July 2nd. 〔正〕 I arrived in New York on July 2nd.
〔析〕 at用来表达较小的地方，而in用来表达较大的地方。at常用于at the school gate, at home, at a bus stop, at the station, at the cinema, at a small village。
46.〔误〕 He lived in No. 3 Beijing Road. 〔正〕 He lived at No. 3 Beijing Road.
〔析〕 在门牌号码前要用at, 并要注意它的惯用法：at the end of the street, at the foot of the mountain, at the top of the page。
47.〔误〕 There is a colour TV set at the corner of the hall. 〔正〕 There is a colour TV set in the corner of the hall.
〔析〕 在屋内的角落应用in，而墙的外角用at，如：There is a tree at the corner of the street.
48. 〔误〕 Do you know there is some good news on todays newspaper? 〔正〕 Do you know there is some good news in todays newspaper? 〔析〕 在报纸上的新闻要用in, 而在具体某一版上，或某一页上则要用on。
49. 〔误〕 The school will begin on September 1st. 〔正〕 School will begin on September 1st.
〔析〕这里的school应看作不可数名词泛指学校的课程，即开学之意。要注意，有些活动场所当表达正在从事该种活动时不要加冠词，如：at table (吃饭)， When I came to Toms home, they were at table. 还有： at desk (学习)，at work (工作) at school (上学)， in hospital (住医院) at church 作礼拜如加上定冠词则另有他意，如：at the school 即在学校工作或办事，in the hospital 即在医院工作或去看望病人。
50. 〔误〕 Ill leave Beijing to Shanghai tomorrow. 〔正〕 Ill leave Beijing for Shanghai. 〔正〕 Ill leave for Shanghai.
〔析〕 leave for 是离开某地去某处的固定搭配，不可将for改为别的介词。这样的搭配还有：start for 动身前往某处，set out for， sail for。
51. 〔误〕 Im sorry. I have to get out the bus at next stop. 〔正〕 Im sorry. I have to get out of the bus at next stop.
〔析〕 get in, 与 get out是两个相反的词组。get in 为上车，而get out为下车，但语法家认为这里的in与out为副词，所以其后不能接名词，我们可以讲Wed better get in. 或Wed better get out. 还有一组词组有关上下车：get on/off(a train, a ship, a struck) get into/out of (a car, taxi…)