a: 

=>Phương trình vô nghiệm

b: 

(vô lý)

=>Ptvn

c: 

mà |x|>=0 với mọi x

nên 

d: 

=>2=3(vô lý)

e: (vô lý)

28A

29B

30C

31C

32D

a: Ta có: 

Do đó: Hai pt này tương đương

b: Ta có: 

=>Hai pt này ko tương đương

starts-ends

Have-slept, had rung

rises, is rising

hasn't been has lived

has got

gets

belongs

remember

1. If they were not late, they would not catch a taxi.

2. If Peter didn't go to class late, he would not be punished.

3. If you moke, you'll have a cough.

4. After they cleaned the house, they cooked dinner.

5 A festival is being celebrated 

6His car has been cleaned.

7 A party are going to be held to welcome the new year's coming.

8 If I had enough money, I would buy that book.

<=>

<=>

<=>13x-4=90

<=>13x=94

<=>x=

x≠−1,x≠2⇔2x−4−x−1=3x−116=2xx=6:2=3(tmđk)

1.D

2.B

3.A

4.B

5.A

B