课文详注 Further notes on the text
1.I believe that this house is for sale. 我想这房子是要出售的吧!
believe是“相信”、“认为”的意思，后可跟某人或名词性从句。如：
I believe you. 我相信你(说的话)。
I believe that he has already gone to London. 我认为他已经去伦敦了。
for sale意为“供新概念”、“待售”。
2.How long have you lived here? 您在这里住了多长时间?
how long常用于询问时间的长短与物体的长度。
3.since 1976, 从 1976年起。
这是介词短语，since在这里是介词。用这个介词短语作时间状语的句子中，谓语要用完成时。(请参见本课语法部分。)
4.How much does this house cost? 这座房子卖多少钱?
how much常用于询问东西的新概念。 cost是指得到一件东西所花费的钱，其真正的价值可能低于或高于所要的价。这种新概念主要是指商店内的标价或货主索要的新概念。相比之下，worth (prep.)主要是指某物的本身价值。
5.…I can'T decide yet.……我还不能决定。
句中的yet常见于否定句，表示“迄今仍未”的意思。
for与 since
现在完成时还可以描述发生在过去且一直延续到现在的动作，这种动作甚至有可能延续下去。在这种情况下，它一般与for+ 一段时间、since+ 某个时间点连用。
请注意：for+ 一段时间表示某个动作持续多长时间;since+ 某个时间点表示某个动作是何时开始的。
1.retire v.
(1)退休;离职：
He retired at the age of 60. 他60岁时退休了。
He's going to retire soon from the sea. 不久他将退休，结束其航海生涯。
(2)退出;退隐：
He often retires to his country house at weekends. 他周末通常到他那个乡间别墅生活。
The ladies retired, and the gentlemen went on drinking and chatting. 女士们离席退出，先生们则继续喝酒聊天。
2.worth prep.
(1)相当于……价值，值……钱：
The new house would be worth 50, 000 pounds. 这座新房子会值50，000英镑。
How much is the necklace worth? 这条项链值多少钱?
(2)具有……价值;值得：
That city is worth visiting. 那座城市值得一游。
Is the film worth seeing? 这部电影值得一看吗?
Lesson 90
A
1 Did the sun set at twenty past seven?
The sun didn't set at twenty past seven.
2 Did he eat his lunch at one o'clock?
He didn't eat his lunch at one o'clock.
3 Did they do their homework last night?
They didn't do their homework last night.
4 Did he come by car this morning?
He didn't come by car this morning.
5 Did the sun rise at half past five?
The sun didn't rise at half past five.
6 Did you swim across the river yesterday?
We didn't swim across the river yesterday.
B
1 Yes, I did my homework last night.
He hasn't done his homework yet.
2 Yes, Mrs. Jones went to the butcher's this morning.
Mrs. Williams hasn't been to the butcher's yet.
3 Yes, I spoke to him yesterday.
She hasn't spoken to him yet.
4 Yes, George swam across the river an hour ago.
Sam hasn't swum across it yet.
5 Yes, I saw that film yesterday.
Sam and Penny haven't seen that film yet.
6 Yes, Tim took off his shoes a minute ago.
Frank hasn't taken off his shoes yet.