A salesman explains a new product. 销售员说明新产品。

(1) 改为以 I 为主语的现在进行时的句子
—> I'm explaining a new product. 我正在说明新产品。

(2) 改为以 He 为主语的过去时的疑问句
—> Did he explain the new product? 他说明新产品了吗？

(3) 改为以 Who 开头的过去时疑问句
—> Who explained the new product? 谁说明了新产品？

Everyone comes back from lunch. 大家吃完午餐回来。

(1) 改为过去时的疑问句
—> Did everyone come back from lunch? 大家吃完午饭回来了吗？

(2) 改为“还没有人回来。”的现在完成时的句子
—> No one has come back from lunch yet.

(3) 改为以 When “什么时候”开头的将来时疑问句
—> When will everyone come back from lunch? 大家什么时候吃完饭回来？

The office clock is ten minutes fast. 办公室的时钟快十分钟。

(1) 改为疑问句
—> Is the office clock ten minutes fast?

(2) 改为附加疑问句
—> The office clock is ten minutes fast, isn't it?

(3) 把 The office 改为 Your watch “你的手表”，并改为“慢十分钟”
—> Your watch is ten minutes slow. 你的表慢了十分钟。

The client placed a large order. 客户订了大量的货。

(1) 改为疑问句，时态还是过去时
—> Did the client place a large order? 客户订了大量的货吗？

(2) 句子开头加入 I wish “我希望……” 提示: 时态要用过去完成时，表示与过去事实相反的愿望
—> I wish the client had placed a large order. 我希望客户订了大量的货。

(3) 改为以 When “什么时候”为开头的过去时疑问句
—> When did the client place a large order? 客户什么时候订了大量的货呢？

It seems like it's going to get hot today. 今天看起来会很热。

(1) hot 换为 cold
—> It seems like it's going to get cold today.今天看起来会很冷。

(2) 改为疑问句
—> Does it seem like it's going to get hot today? 今天看起来会很热吗？

(3) 把 get hot 改为 rain，再把 today 换成 soon
—> It seems like it's going to rain soon. 看起来很快会下雨。

I go up by the elevator. 我搭电梯上去。

(1) 主语改为 he
—> He goes up by the elevator. 他搭电梯上去。

(2) 改为否定句
—> I don't go up by the elevator. 我不搭电梯上去。

(3) 把第一句 he 为主语的句子前面加 I saw
—> I saw him go up by the elevator. 我看见他搭电梯上去。

This ticket machine is broken. 这台售票机坏了。

(1) 改为疑问句 

—> Is this ticket machine broken?

(2) 句子开头加 I wonder if 我想知道是不是……/ 我怀疑是否……

—> I wonder if this ticket machine is broken.

(3) 改为以 someone “有人/某个人”为主语的主动式句子，时态为过去时

—> Someone broke this ticket machine. 有人把这台售票机弄坏了。

There are no seats on the bus. 公共汽车上没有空位。

(1) 将 no 改为 some 的肯定句

—> There are some seats on the bus.

(2) 改为疑问句

—> Are there no seats on the bus? 公共汽车上没有空位吗？/

      Are there any seats on the bus? 公共汽车上有空位吗？

(3) 改为用 must “应该……”做助动词的句子

—> There must be no seats on the bus.

I'd better run so I can make the light. 我最好在信号灯变换之前跑过去。

(1) 主语改为 We

—> We'd better run so we can meke the light.

(2) 用 have to...“应该……”（提示: 用 have to 替换 'd better “最好……”）

—> I have to run so I can make the light.

(3) make the light 改为 catch the light

—> I'd better run so I can catch the light.

My train pass has expired. 我的月票过期了。

(1) 改为附加疑问句

—> My train pass has expired, hasn't it?

(2) 改为 when 开头的疑问句

—> When did my train pass expire? 我的月票什么时候过期了？

(3) 改为否定句

—> My train pass hasn't expired yet. 我的月票还没有过期。

I shouldn't have stayed up late. 我不该那么晚才睡。

(1) 句首加 I wish

—> I wish I hadn't stayed up late.

I wish “我希望……”后面要变成和事实相反的过去完成时。

(2) 改为表示事实的肯定句

—> I stayed up late.

(3) 改为含有 be going to 和 tonight 的将来时肯定句

—> I'm going to stay up late tonight.

I jog. 我慢跑。

(1) 主语改为 he
—> He jogs.

(2) 主语改为 you，再改为现在完成时的疑问句
—> Have you (ever) jogged?
改为 you 为主语就是 You jogged，变成现在完成时就是 You have jogged，再变成疑问句就是 Have you jogged? 可以加个 ever 就是 Have you ever jogged?

(3) 主语改为 she，改为现在进行时疑问句
—> Is she jogging?
she 为主语就是 She jogs. 现在进行时就是 She is joking，再变成疑问句就是 Is she jogging?

I have trouble waking up in the morning. 早上起来对我而言是件苦事。/ 早上起床很困难。

(1) 改为否定句
—> I don't have trouble waking up in the morning.
因为这里的 have 是实义动词，所以用 don't 表示否定。

(2) 主语改为 you，并改为以 why 开头的疑问句 
—> Why do you have trouble waking up in the morning?
先改成 you 为主语，就是 You have trouble waking up in the morniing，然后变成 why 疑问句 Why do you have trouble waking up in the morning? 因为是特殊疑问句，所以句尾读降调。

(3) 主语改为 Jim（吉姆），再改为疑问句
—> Does Jim have trouble waking up in the morning?
先用 Jim 做主语，要用第三人称单数，就是 Jim has trouble waking up in the morning，然后变成疑问句 Does Jim have trouble waking up in the morning?

I love the smell of coffee. 我喜欢咖啡的香味。

(1) 主语改为 she

—> She loves the smell of coffee.

(2) 主语改为 he，再改为疑问句 

—> Does he love the smell of coffee?

(3) 主语改为 you，并改为附加疑问句

—> You love the smell of coffee, don't you?

My face looks awful. 我的脸好难看。

(1) 改为疑问句

—> Does my face look awful?

(2) 主语改为 their faces

—> Their faces look awful.

(3) 改为附加疑问句

—> My face looks awful, doesn't it?

It's cold this morning. 今天早上好冷。

(1) 改为过去式
—> It was (It's) cold this morning.

(2) 改为附加疑问句/反义疑问句
—> It's cold this morning, isn't it?
附加疑问句/反义疑问句的句型是:
如果是肯定句: 主句肯定陈述句+否定附加疑问句
如果是否定句: 主句否定陈述句+肯定附加疑问句
比如，..., aren't you? / ..., didn't they? / ..., is he?
附加疑问句常用于征求对方的同意或者确认什么事情。

(3) this moring 换成 last night，并且改为疑问句
—> Was it could last night?
先把 this moring 换成 last night 就是 It's cold last night. 再换成疑问句就是 Was it could last night?

第6个中心句

Supper's ready. 晚餐准备好了。

请说出下面三种动作:

大家就坐。

--> Everybody sits down /

     Everybody takes a seat. （这里是把 everybody “所有人”当成一个整体（单数），所以后面用 sits 和 takes）

孩子们谈谈有关学校的事。

--> The children talk about school.

狗在桌下摇尾巴。

--> The dog is wagging his tail under the table.（wagging his tail 是“摇（他的）尾巴”，也可以是 wagging her tail，也可以用动物“它” wagging its tail，不用分性别）

请说出以下三种心理活动:

我最后一次和家人一起吃晚饭是什么时候呢？

--> When was the last time I had dinner with my family?

小心！你会把汤洒在地上。

--> Be careful! You're going to spill the soup.（提醒别人注意时还经常会用“Watch out (it)!”这个词组。spill 是“溅在……，洒在……”）

不要担心，我会给你一片肉。

--> Don't worry. I'll give you a piece of meat.（“一片肉”是 a piece of meat，如果是“一块肉”是 a chunk of meat）