一课一题一语法：新概念英语第2册第45课
Hello，大家好！欢迎来到“新概念英语的教与学”！我是上海时学教育的钟老师。下面是我们每周一课一题一语法的分享时间，先来公布上一期课后一题的答案及简析：
上一期分享的文章，大家可以点击这里回看：
下面我们继续本周《新概念英语2》第45课的重点句型或语法的分享。先来读一读课文：
一、课文原文
Lesson 45 A clear conscience
The whole village soon learnt that a large sum of money had been lost. Sam Benton, the local butcher, had lost his wallet while taking his savings to the post office. Sam was sure that the wallet must have been found by one of the villagers, but it was not returned to him. Three months passed, and then one morning, Sam found his wallet outside his front door. It had been wrapped up in newspaper and it contained half the money he had lost, together with a note which said: 'A thief, yes, but only 5o per cent a thief!' Two months later, some more money was sent to Sam with another note: 'Only 25 per cent a thief now!' In time, all Sam's money was paid back in this way. The last note said: 'I am 100 per cent honest now!'
——选自《新概念英语》第二册，外语教学与研究出版社，1997年10月第1版
二、重点句型或语法
本课主要为复习课，复习第10课，第21课和第34课的重点语法内容——被动语态，要注意被动语态的基本结构为：
受动者+be+done+by+施动者
下面我们就通过一些例句来进行梳理复习。
（一） 第10课
在第10课里，主要学习的是不同时态中的被动语态，用法上注意主要通过be 的形式变化体现出来，其人称和数方面应与主语保持一致。 比如：
一般现在时：
be动词在该时态中形式变化为：am / is / are+ done 比如：
It is called a clavichord.
它被称作古钢琴。
一般过去时：
be动词在该时态中形式变化为：was / were + done 比如：
The instrument was bought by my grandfather many years ago.
这些乐器是我祖父很多年以前买的。
现在进行时：
be动词在该时态中形式变化为：am/ is/ are+ being+ done 比如：
These instruments are being repaired by a friend of my father's. 这些乐器正在被我父亲的一个朋友修理。
现在完成时：
be动词在该时态中形式变化为：have / has +been + done 比如：
All the preparations for the task have been completed. 所有为这个任务的准备都完成了。
过去完成时：
be动词在该时态中形式变化为：had+ been+ done 比如：
A large sum of money had been lost. 一大笔钱丢了。
（二）第21课
在第21课里，主要学习的是情态动词与被动语态的连用，其基本用法为：受动者+情态动词+be done by+施动者，比如：
The baby can be taken good care of by his mother. 这个宝宝可以被他妈妈照顾得很好。
The wallet must have been found by one of the villagers.
这个钱包一定是被某个村民捡到了。
The flowers should be watered every day.
花应该每天浇水。
（三） 第34课
在第34课里，主要学习的是“动词+宾语+to do” 结构变为被动语态的用法，其基本用法为：受动者+be done by+施动者+to do。其中，施动者经常省略，所以其用法一般简化为：受动者+be done to do。比如：
They asked me to make a speech. 他们请我去做一个演讲。
这句话转换为被动语态为：
I was asked to make a speech. 我被请去做一个演讲。
Mum told him to finish homework. 妈妈告诉他要完成作业。
这句话转换为被动语态为：
He was told to finish homework. 他被告知要完成作业。
The teacher allowed the children to play basketball after shcool.
老师允许孩子们放学后打篮球。
The children were allowed to play basketball after school. 孩子们被允许放学后打篮球。
【注意】
有些双宾动词（如give、pass、buy、send等），用在被动结构时有两种被动形式，即动词的直接宾语和间接宾语都可以作为受动者。比如：
Her father gave her a book .
她爸爸给她一本书。
这句话转换为被动语态：
She was given a book by his father.
A book was given to her by her father.
三、一课一题
根据本课的重要语法点，让我们来练一练吧，请选择正确的选项。
The room must _______ yesterday, for it is very tidy now.