Could you show me how to do this exercise? – Sure!

Mary sometimes has homeworks after doing aerobics.

 Đặt 1/4 + 1/8 + 1/16 + 1/32 + 1/64 =A 

=> 2A = 2.(1/4 + 1/8 + 1/16 + 1/32 + 1/64)

=> 2A = 1/2 +1/4+1/8+1/16+1/32

=> A= 2A-A =  1/2 +1/4+1/8+1/16+1/32 - 1/4 - 1/8 - 1/16 - 1/32 - 1/64

=> A =  1/2 - 1/64 =31/64

In folklore, there are many popular stories about monsters.

The teacher tells us to use a pencil to write our names on the paper.

-Đúng đầu bài không bạn?

1. My sister is old. She can drive.

=> My sister is old enough to drive.
2. The radio isn't small. You can't put it in your pocket.

=> The radio isn't small enough for you to put it in your pocket.
3. This coat isn't warm. I don't wear in it winter.

=> This coat isn't warm enough for me to wear it in winter.
4. She is beautiful and intelligent. She can become Miss word.

=> She is beautiful and itelligent enough to become Miss word.
5. The weather was fine. We could go camping.

=> The weather was fine enough for us to go camping.

bạn cần nói rõ đề hơn : giảm cạnh hình vuông thế nào: giảm 1 cạnh hình vuông hay 2 cạnh

ví dụ: 

Lên men m kg gạo nếp (chứa 80% tinh bột), thu được rượu etylic và V lít khí CO₂ (đktc). Hấp thụ hoàn toàn  1 1000 lượng khí CO₂ vào 170 ml dung dịch NaOH 0,5M thu được dung dịch chứa 4,44 gam chất tan. Biết hiệu suất mỗi giai đoạn trong quá trình lên men là 80%. Giá trị của m là

A. 5,06.

B. 12,66

C. 6,33

D. 7,03

1. Mr Long worked in that factory in 1995.

2. Lan and I are student.

3. Has your brother been to Ha Noi yet?

4. Her grandmother is reading a magazine.

5. They didn't take that train last week.

6. Are you doing your home work now?

7. The exercise is difficult so I can't do it.

8. Doesn't Hoa have English on Monday?

9. How long has your mother lived in Ha Noi?

10. The weather was very bad so we stayed at home.