Chu vi hình chữ nhật là :

(24+21)x2 =90(cm)

Đáp số: 90 cm

là mùi hương

1d

2b

a, 18 giờ

b,540 tấn 0 tạ

c,5060000cm2

d,80 năm

1 a

2c

1 a

2c

1c

2a

3b

4a

7  

\(\dfrac{6}{3}\),\(\dfrac{10}{5}\)

4 did-start

5 didn't see

6 has already done

7 am doing

8 is

9 is, will-do

10 starts

11 is increasing

12 will come

13 has visited

14 does-do

15 are-going to do, am going to visit

16 have-known, have known

17 haven't seen, were

18 am going

19 Have-met

đoạn thơ nào ạ

50-2+1=50+1=51