Cho tam giác nhọn ABC. H là trực tâm, dựng hình bình hành BHDC, I là giao 2 đường chéo HC và BD.

a)chứng minh: 4 điểm A,B,C,D cùng thuộc 1 đường tròn.

b) O là tâm đường tròn ngoại tiếp tam giác ABC, so sánh góc BAH và góc OAC.

c)AI cắt OH tại G. Chứng minh G là trọng tâm tam giác ABC.

1,"Can you speak Vietnamese, Maryam?"Nga asked.

->Nga asked.......

2,Why don't we go to the countryside this weekend?

->Minh suggested.......

3,I would rather watch TV than go to the cinema.

->I prefer......

4,"Where will you spend your vacation next year? "Liz said to us.

->Liz asked us........

5,I can do what i want and you can't stop me.

->You can't.......

6,Please don't interrupt me all the time.

->Would you mind.......

7,My father said I could use his car.

->My father allowed.....

8,It's not a good idea to travel during the rush hour.

->It's better to avoid......

The doctor advised him to stay in bed for a few days.

He......

I regretted not telling him what happened last night.

I wish......

He hasn't been back to his village for over 20 years.

It's......

Spending the weekend in the country side is very exciting.

It's....

Practice speaking English every day or you can't improve your English.

If....