The roof of the building was held up by a row of thick stone columns.

Tuần trước , thầy giáo nói em và các bạn vẽ ước mơ của em . Lúc đầu em còn không biết vẽ , lúc sau , Nga đã dạy em vẽ và bức tranh đã được hoàn thiện xong . Em cảm thấy rất vui . 

Thế này được khum ?

cũng đc á

12.There are four seasons in our country.

12. There are four seasons in our country.

Dịch: Đất nước chúng tôi có bốn mùa.

I want to do something exciting.

turn the following sentences into negative sentences and questions

1.(+)he is listening to music

(-)____He isn't listening to music_________________________________________________

(?)__Is he listening to music?___________________________________________________

2.(+)they are wearing jeans

(-)_____They aren't wearing jeans________________________________________________

(?)_______Are they wearing jeans?______________________________________________

3(+)Elizabeth is sweeping the floor.

(-)____Elizabeth isn't sweeping the floor_________________________________________________

(?)____Is Elizabeth sweeping the floor?_________________________________________________

4(+)It is raining cats and dogs today

(-)____It isn't raining cats and dogs today_________________________________________________

(?)______Is it raining cats and dogs today?_______________________________________________

5(+) my family is going to the park right now

(Câu này bạn bổ sung thêm chữ now nữa nha)

(-)_____My family isn't going to the park right now_______________________________________________

(?)_____Is your family going to the park right now?________________________________________________

6(+)the children are listening to their teacher

(-)____The children aren't listening to their teacher_________________________________________________

(?)______Are the children listening to their teacher_______________________________________________

7(+)a man is selling ice-cream in the park

(-)______A man isn't selling ice-cream in the park_______________________________________________

(?)______Is a man selling ice-cream in the park?_______________________________________________

8(+) the girls are dancing

(-)______The girls aren't dancing_______________________________________________

(?)____Are the girls dancing?_________________________________________________

9(+)pupils are talking to each other

(-)____Pupils aren't talking to each other_________________________________________________

(?)____Are pupils talking to each other?_________________________________________________

10(+)I am doing the washing-up

(-)______I am not doing the washing-up_______________________________________________

(?)____Are you doing the washing up?_________________________________________________

a, \(CH_4+2O_2\underrightarrow{t^o}CO_2+2H_2O\)

\(C_2H_4+3O_2\underrightarrow{t^o}2CO_2+2H_2O\)

b, Ta có: n_CH4 + n_C2H4 = 0,5 (1)

Theo PT: \(n_{CO_2}=n_{CH_4}+2n_{C_2H_4}=\dfrac{30,8}{44}=0,7\left(mol\right)\left(2\right)\)

Từ (1) và (2) \(\Rightarrow\left\{{}\begin{matrix}n_{CH_4}=0,3\left(mol\right)\\n_{C_2H_4}=0,2\left(mol\right)\end{matrix}\right.\)

c, \(C_2H_4+Br_2\rightarrow C_2H_4Br_2\)

_____0,2____0,2 (mol)

⇒ m_Br2 = 0,2.160 = 32 (g)

d, \(d_{Y/H_2}=\dfrac{\dfrac{0,3.16+0,2.28}{0,5}}{2}=10,4\)

Câu 2:

a, Gọi CTPT cần tìm là C_nH_2n

⇒ 14n = 42

⇒ n = 3

Vậy: CTPT cần tìm là C₃H₆.

b, Ta có: \(n_{C_3H_6}=\dfrac{3,7185}{24,79}=0,15\left(mol\right)\)

PT: \(2C_3H_6+9O_2\underrightarrow{t^o}6CO_2+6H_2O\)

____0,15__0,675___0,45 (mol)

\(\Rightarrow V_{O_2}=0,675.24,79=16,73325\left(l\right)\)

c, \(CO_2+Ca\left(OH\right)_2\rightarrow CaCO_3+H_2O\)

____0,45________________0,45 (mol)

⇒ m_CaCO3 = 0,45.100 = 45 (g)

There is a beautiful garden with many tall trees and flowers at my school