6.”what should I do with the problems?” said he

A.He said he didn’t know what should to do with the problems

B.He said he didn’t know what should he do with the problems

C.He said he didn’t know what should do with the problems

D.He said he didn’t know what to do with the problems

George is the most dependable person I've ever met

Your mother is the most kind-hearted person

Mr John is the best teacher in this school

Life in the city is more interesting than that in the countryside

Ta có: \(n_{Ca\left(OH\right)_2}=\dfrac{m_{Ca\left(OH\right)_2}}{M_{Ca\left(OH\right)_2}}=\dfrac{120}{74}=\dfrac{60}{37}\left(mol\right)\)

a)Ta có: 

\(Ca\left(OH\right)_2+2HCl\rightarrow CaCl_2+2H_2O\)

60/37            120/37       60/37

Ta có: \(mCaCl_2=nCaCl_2.MCaCl_2=\dfrac{60}{7}.111=180\left(g\right)\)

Đổi 500ml=0,5l

\(C_{M_{HCl}}=\dfrac{120}{37}:0,5=\dfrac{240}{37}M\)

a) Xét tứ giác ABDC, ta có:

AM=MD (D đối xứng với A qua M)

BC=CM (M là trung điểm của BC)

=>ABDC là hình bình hành (Dấu hiệu nhận bt hình bình hành)

b) Ta thấy: Tứ giác ABDC là hình bình hành có 2 đường chéo AD, BC

=>ABDC là hình thoi <=> AD⊥BC 

c) Nếu BC=2AM => BC=AD (Vì cùng bằng 2AM)

=>ABDC là hình chữ nhật (Dấu hiệu nhận biết hình chữ nhật)

1 A

2 B

3 B

4 C

5 A

6 B

7 A

8 D

9 A

10 B

Nam is Phong's brother

The garden has six flowers 

The door is in front of the cat

Between the chair and the bed is the table

1 C

3 A

4 C

8 C

9 A

10 B

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S + be + adj (not) + to + V 

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Viết lại câu dạng 2 thì HTHT:

Tam used to type faster than she does now