1. A

2. B

3. C

1. does -> do

2. is-> are

3. used -> use

4. By -> in

Yesterday, I spent two hours doing the homework

Spost

Because of raining heavily, the boy had to stop playing soccer .

a little

little

a lot of

classmate

a = x( x³ - 4x² + 8x - 16)

c, (ab - xy)² - (bx - ay)² 

dựa theo hằng đẳng thức a² - b² = ( a + b)(a - b)

=> = [ ( ab - xy) + ( bx - ay)] . [ ( ab - xy) - ( bx - ay) ]

tương tự làm câu d theo câu c