1. Tom__________(go) to his friend's house, but the boys __________(not be) there. They_________(play) soccer in the vacant lot down the street.

2. _________(you/ listen) to the teacher when she__________(explain) this exercise?

3. It(be)__________beautiful yesterday when we___________(go) for a walk in the park. The sun____________(shine). The birds__________(sing).

4. My brother and sister__________(talk) about something when I___________(walk) into the room.

1. went - weren't - were playing

2. Did you listen - was explaing

3. was - went - was shining - were singing

4. were talking - walked

------------------------

` 1`. went/weren't/were playing

` 2`. Did you listen/she was explaining

` 3`. was/went/was shining/was singing

` 4`. were talking/walked

` ------------`

` @` Quá khứ đơn

Với V thường

` (+)` S + V-ed/V2 + ...

` (-)` S + didn't + V-inf + ...

` (?)` Did + S + V-inf + ...?

Với V tobe

` (+)` S + was/were + ...

` (-)` S + was/were + not + ...

` (?)` Was/were + S + ...?

` @` Quá khứ tiếp diễn

` (+)` S + was/were + V-ing + ....

` (-)` S + was/were + not + V-ing + ...

` (?)` Was/were + S + V-ing + ...?