Cho đoạn thẳng AB có trung điểm I. Kẻ đường thẳng d vuông góc với AB tại I. Trên d lấy 2 điểm C,D sao cho điểm C nằm giữa 2 điểm D và I.
a) Chứng minh tam giác CIA= tam giác CIB
b) Chứng minh DI là phân giác của góc ADB
c) Kéo dài AC cắt DB tại M. Kéo dài BC cắt AD tại N. Chứng minh rằng MN song song với AB.
Bài 1 : Chuyển thành câu có nghĩa không đổi :
1.Studying English culture is interesting
I find it
2.Nam said,"Why don't we go swimming this afternoon?"
Nam suggested
3.The word is so difficult that we can't spell it
It's such
4.The keepers feed the lions at 5p.m every day.
The lions
5.Although she passed the exam, she didn't feel satisfied
Despite
6.It's a pity that I don't have bicycle.
I wish
7.Practise speaking English every day, and you'll speak it fluently.
If you
8.We like to lie on the beach all the day.
We enjoy
9.I regretted that I told him about my sorrow.
I regretted
10.This book is interesting, but she doesn't like reading it.
Despite
11.Although the weather was bad, they went swimming.
Despite
12.He often played piano at night.
He used to
13.It's three months since she started learning French.
She
14.Unless you are late again, I will punish you.
If
15."You should look after your parents better" she said.
She suggested
16.She would rather read a book than watch TV.
She prefers
17.We can't buy this house because we don't have enough money.
If we
18.It's three months since she started learning German.
She has
19. I haven't eaten this kind of food before.
This is the first time
20.If you don't take the taxi, you will be late for the meeting.
Unles
21.What a pity you can't take part in our trip.
I wish