Tìm và sửa lỗi sai

I

1.The doctor told my father (stop smoking) because of his sickness

-> to stop smoking

2.I haven't seen her (when) we left school

-> since

3.She walked (ten kilometer) a day to get water for her family

-> ten kilometers

4.That is the girl whom Jim wants (to marry her)

-> to marry

II

1.My uncle doesn't care how much (does the car cost);he is buying it anyway

-> the car costs

2.Stop making so much noise or the neighbor will get (angrily)

-> angry

III

1.The Path Finder , a magazine for teengers , is (of one) my favorite magazines

-> one of

2.I sent him a letter of apology,but he still seened (angrily)

-> angry

3.Nga wishes she (can go) camping with her classmates this weekend

-> could go

4.Mary learned very hard for the lesson ,(because) she passed the exam quite easily

-> so

5.The Internet can also be very dangerous (because) virues and bad programs

-> because of

IV

1.If I (heard) any news,I'll phone you

-> hear

2.Mrs.Lien,(whom) sings very well,is my teacher of English

-> who

3.This is the city (which) I was born

-> where

4.They are the people (who) cars were stolen

-> whose

5.She asked me if I (live) in Hanoi

-> lived

V

1.She would come to see you if she (has) your address

-> had

2.You must (starting) your job as soon as possible

-> start

3.Don't forget to (turn on) all the lights when you go to bed

-> turn off

VI

1.The questions which the teacher wrote on the board (was) not easy

-> were

2.I think your grey hair makes you look rather (distinguishing)

-> distinguishable

VII Sắp sếp

1.It/be/beautiful day Lan / ne/outside/play/her dog/Skippy

-> It was a beautiful day and Lan was outside playing with her dog Skippy.

2.Lan's mother /gather/family/and tell them/find shelter/house

-> Lan's mother gathered her family and told them to find the shelter in the house.

3.All of a sudden /sky/become/dark.Storm/come/strong wind/heavy rain.Lan/be scare/but soon/storm finish.Everyone/be glad

-> All of a sudden, the sky became dark. A storm came with strong wind and heavy rain. Lan was scared but soon the storm finished. Everyone was glad.

Ta có: \(\sqrt{ab}=\sqrt{a}\sqrt{b}\left(a,b\ge0\right)\)

Công thức căn số này không thể áp dụng cho số âm. Ở đây a = b = -1

Nên \(\sqrt{\left(-1\right)\left(-1\right)}\ne\sqrt{-1}\sqrt{-1}\)

Vậy phép chứng minh trên sai ở bước \(2=1+\sqrt{-1}\sqrt{-1}\)