I live in a very old town which is surrounded by beautiful woods. It is a famous beauty spot. On Sundays, hundreds of people come from the city to see our town and to walk through the woods. Visitors have been asked to keep the woods clean and tidy. Litter baskets have been placed under the trees, but people still throw their rubbish everywhere. Last Wednesday, I went for a walk in the woods. What I saw made me very sad. I counted seven old cars and three old refrigerators. The little baskets were empty and the ground was covered with pieces of paper, cigarette ends, old tyres, empty bottles and rusty tins. Among the rubbish, I found a sign which said, 'Anyone who leaves litter in these woods will be prosecuted!'
1．is surrounded by，由……环绕着。
2．hundreds of people，数以百计的（游）人。
3．Visitors have been asked to keep the woods clean and tidy．游客已被告知要保持树林的整洁。
句中 have been asked是被动bv伟德国际体育态的完成时结构。（详见本bv伟德国际体育bv伟德国际体育法部分。）to keep the woods clean and tidy是动词不定式短bv伟德国际体育，作主bv伟德国际体育visitors的补足bv伟德国际体育。clean and tidy 是宾bv伟德国际体育 the woods 的宾bv伟德国际体育补足bv伟德国际体育。
4．go for a walk，去散步。
5．What I saw made me very sad．我所见到的一切使我非常难过。
句中的主bv伟德国际体育What I saw 是 what 引导的名词性从句。
throw( threw; thrown)
被动bv伟德国际体育态的构成： be +过去分词。
（1）一般现在时形式： am/are/is +过去分词：
The room is aired regularly.
The knives are sharpened regularly.
（2）一般过去时形式： was/were +过去分词：
She was dressed in red.
The windows were opened this morning.
amuse, embarrass, worry, surprise, interest, upset等：
She is embarrassed.
They were worried.
六、lesson 144 练习答案
1 The writer lives in a very old town which is surrounded by beautiful woods.
2 Because it is a famous beauty spot.
3 Visitors have been asked to keep the woods clean and tidy.
4 Litter baskets have been placed under the trees.
5 The writer went for a walk in the woods.
6 Yes, he saw a lot of rubbish.
7 He saw a sign among the rubbish.
8 The sign said, ‘Anyone who leaves litter in these woods will be prosecuted.
1 Someone has aired it. It has already been aired.
2 Someone has cleaned them. They have already been cleaned.
3 Someone has emptied it. It has already been emptied.
4 Someone has sharpened it. It has already been sharpened.
5 Someone has turned them on. They have already been turned on.
6 Someone has bought them. They have already been bought.
7 Someone has swept it. It has already been swept.
8 Someone has taken them to school. They have already been taken to school.
9 Someone has invited them. They have already been invited.
10 Someone has told them. They have already been told.
1 It hasn't been aired yeet. It will be aired tomorrow.
2 They haven't been cleaned yet. They will be cleaned tomorrow.
3 It hasn't been emptied yet. It will be emptied tomorrow.
4 It hasn't been sharpened yet. It will be sharpened tomorrow.
5 They haven't been turned on yet. They will be turned on tomorrow.
6 They haven't been watered yet. They will be watered tomorrow.
7 It hasn't been repaired yet. It will be repaired tomorrow.
8 It hasn't been dusted yet. It will be dusted tomorrow.
9 They haven't been corrected yet. They will be corrected tomorrow.
10 It hasn't been shut yet. It will be shut tomorrow.