1. She (do) her homework now. ......................................................................................................... 2.Nga ( buy) a new book last week. ......................................................................................................... 3. They ( visit) Hue yet? ......................................................................................................... 4. Mai usually ( go) to school on time. .........................................................................................................

`1`. She (do) her homework now.

$\rightarrow$ She is doing her homework now.

Dấu hiệu: now

=> Thì hiện tại tiếp diễn.

Cấu trúc: S + to be + V_ing + ......

`2`. Nga ( buy) a new book last week.

$\rightarrow$ Nga bought a new book last week. 

Dấu hiệu: last week

=> Thì quá khứ đơn

Cấu trúc: S + V_ed/V2 + ...

Buy( v1): bought( v2)

`3`. They ( visit) Hue yet?

$\rightarrow$ Have they visited Hue yet?

Dấu hiệu: yet

=> Thì hiện tại hoàn thành 

Cấu trúc: Have/has + S + V3/V_ed + ..........

`4`. Mai usually ( go) to school on time.

$\rightarrow$ Mai usually goes to school on time.

Dấu hiệu: usually

=> Thì hiện tại đơn

Cấu trúc: S + V1/s/es + ..........