Giúp mình nhé III. IDENTIFY THE MISTAKE IN EACH SENTENCE. (5 PTS)

1. Asteroids may be fragments (A) of a planet shattered (B) long ago (C) or from material->of material (D) the nuclei of old comets.

2. Between (A) the ages of nine and fifteen, almost (B) all young people undertake->undergo (C) a rapid series of (D) psychological changes.

3. Ponds are noted (A) for their rich and varied types of (B) plant and animal life, all maintain->maintained (C) in a delicate ecological balance (D).

4. The explorers said that (A) they could make->could have made (B) the round trip shorter if (C) the weather had not been that bad (D).

5. The Pinebrook Inn has (A) a courtesy bus which (B) runs every thirty minute->every thirty minutes (C) both to and from (D) the downtown area.

6. Most authorities consider both (A) dreaming while->during (B) sleep and daydreaming to be (C) forms of fantasy (D).

7. Antique auctions(A) are getting more and more (B) popular in the United States because of increasingly->increasing (C) public awareness of the value of (D) investing in antiques.

8. An X-ray microscope enables (A) a person to see on->x (B) solid materials such as (C) metal and bone (D).

9. The growth rate (A) of the Pacific Rim countries is twice faster than (B) other comparable->comparative (C) areas during (D) the Industrial Revolution.

10. Computers have (A) made access (B) to information instantly available (C) just to push->by pushing (D) a few buttons

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Tìm và sửa lỗi sai

1/We should let children to learn->learn how to use the computer as early as possible

2/ People use computers in business ,in->at homes, and in entertainment

3/ Her children have had a good time ever for->together since their arrival

4/ Have you turned the washing machine off already->yet?

5/ computer bulletin boards are used on->in the same way as traditional ones

90 số,tick mk nha

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Lần đầu tiên có người tick tui đấy,cảm ơn!

5/3

510

 gọi vận tốc đoàn tàu so với mặt đất ( vận tôc thực của tàu) là V. 
chọn hệ quy chiếu với người đi xe đạp làm gốc => vận tốc của đoàn tàu lúc đó là V' (là vận tốc của tàu đối với xe đạp) , với V' = V +18 (km/h). 
khi đó, V' = 200m / 12s = 0,2km / (12/3600 (h)) = 60 (km/h) 
=> V' = V + 18 = 60 => V = 42 (km/h) 

+) cách làm của Lò văn Xéng cũng đúng rồi đó, chỉ là bước cuối tính nhầm thôi, ptrình: 
200 : (x+5) = 12 => x = (35/3) (m/s) = 42km/h