a, Số bi cần lấy tổi thiếu để chắc chắn có 3 bi cùng màu là:2+2+3= 7 (viên)

b, Số bi cần lấy tối thiểu để chắc chắn có 3 viên bi khác màu là: 7+9+1=17(viên)

Trường hợp xấu nhất bốc phải:

1bóng đen+1bóng xanh+2bóng vàng+2bóng trắng+2bóng đỏ=9bóng

Để chắc chắn có 3 quả bóng cùng màu thì cần bốc ít nhất số bóng:

           9 + 1 = 10 ( bóng)

Đáp số: 10 bóng

Chu tiểu cường :))

1. My brother watches TV two hours a day.

-> How many hours a day does your brother watch TV ?

2. I like Tu Long best ib the Weekend Meeting shows.

-> Who do you like best in the Weekend Meeting shows ?

3. The news programme often finshes at eighto' clock.

-> What time does the news programme often finish ?

-> When does the news programme often finish ?

4. We watched the late football match on TV last night.

-> What did you watch on TV last night ?

5. The new television is ten thousand million dong.

-> How much is the new television ?

1. My brother watches TV two hours a day.

-> How many hours a day does your brother watch TV ?

2. I like Tu Long best ib the Weekend Meeting shows.

-> Who do you like best in the Weekend Meeting shows ?

3. The news programme often finshes at eighto' clock.

-> What time does the news programme often finish ?

-> When does the news programme often finish ?

4. We watched the late football match on TV last night.

-> What did you watch on TV last night ?

5. The new television is ten thousand million dong.

Đặt câu hỏi cho những từ in đậm trong mỗi câu sau đây:

1. My brother watches TV two hours a day.

How long does your brother watch TV a day?

2. I like Tu Long best in the Weekend Meeting shows.

Who do you like best in the Weekend Meeting shows

3. The news programme often finishes at eighto' clock.

What time does the news programme often finish?

4. We watched the late football match on TV last night.

What did we watch on TV last night?

5. The new television is ten thousand million dong.

How much does the new television cost? 

6. Tom put the remote control on the bookshelf.

Where did Tom put the remote control?

7. They go to the English club twice a week.

How often do they go to the English club?

8. She missed a week's lessons because of illness.

Why does she miss a week's lessons?

9. That newsreader usually gets to work by bus.

How does that newsreader usually get to work?

10. The game show lasted for two hours and a half

How long did the game show last?

1. Jack and Mike are our brothers.
2. Is that his motorbike?
3. These are our postcards.
4. This box of chocolate belongs to her.
5. These apple trees are theirs.

Chọn D

Chọn C