1. Tom and Mike are doing their homework on the third floor at the moment.

2. I can't see anything because my brother is standing in front of me.

3. Linda isn't eating anything because she is full.

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$$HTTD$$

(+): S + am/is/are + V_ing.

(-): S + am/is/are + not + V_ing.

(?): Am/is/are + S + V_ing?

DHNB: at the present, at the moment, now, Listen!, Look!, ...

- S + can + V1 + ...: Tôi có thể ...

@ka

1 Tom and Mike are doing homework on the third floor at the moment .

2  I can't see anything because my brother is standing in front of me .

3  Linda doesn't eat anything because she is full .

- Hành động thường làm ở hiện tại .

=> Hiện tại đơn .

( + ) S + V(s,es) + O ...

( - ) S + do/does + not + V-inf + O ...

( ? ) Do/does + S + V-inf + O ... ?

- Hành động đang diễn ra .

=> Hiện tại tiếp diễn .

( + ) S + is/am/are + V_ing + O ...

( - ) S + is/am/are + not + V_ing+ O ...

( ? ) Is/am/are + S + V_ing + O ... ?