同学你好，该知识点来自沪江网校《英语零基础直达大学六级【双11专享特惠班】》的课程，想要更系统的学习，欢迎进入课程学习。不仅可以和更多的同学一起学习，而且还有老师、助教随时的学习指导和知识点解答哦。

同学你好~

Key to KS Exercises
A
What happened：began(1. 2);examined(1. 4);were not able to
find(1. 5); did not start(1. 6); discovered (1. 7);noticed(1.
8);was wound(1. 8);was able to s olve(1. 9);dropped(1. 10);wound(1.
11);it did so(1. 11);sent(1. 11);started (1. 11)
What has happened：have put out(1. 1)
What has been happening：have been trying to find(1. 2)
C
Jack looked at his watch for the twentieth time. Suddenly Jill
arrived.
‘I've been waitting for over an hour, ’he said angrily. ‘You
never come on time. ’
‘Oh, is that so?’Jill answered. ‘Were you here at 2. 30?’
Jack went red. ‘Well, ’he said, ‘I got here five minutes
late myself, but you weren't here. ’
‘I came here at exactly 2. 30, ’Jill said, ‘and I waited
for five minutes, but you didn't come. ’
‘What have you been doing since then? ’Jack asked.
‘I've just been to the hairdresser's，’Jill answered brightly.
Key to SD Exercises(sample sentences)
a Look：you threw the potato-peeler away by mistake.
The shepherd threw some food to his dogs.
The teacher threw some chalk at a boy who wasn't listening.
b I'm quite certain these are my glasses.
The children are very quiet. What's going on?
c The cause of unemployment are complicated.
Can you explain the reason for changing our arrangements?
He reasoned that we would have to comply, even if we didn't
wish to.
d Please don't drop that vase!
It fell from my hands and broke.
Key to Multiple choice questions
1 c 2 d 3 a 4 c
5 c 6 c 7 d 8 c
9 d 10 a 11 c 12 c
Key to Sentence structure
When it did so, it sent sparks down to the ground.

祝同学学习进步~