$1.$ are

$2.$ have visited

- Mình nghĩ "the first time" diễn tả trải nghiệm nên dùng thì hiện tại hoàn thành.

$3.$ has improve/ left

- S + have/ has + V3 since + Quá khứ đơn.

$4.$ found

$5.$ bought

- "last week" → Thì quá khứ đơn: S + V2.

- "yet" → Thì hiện tại hoàn thành: S + have/ has + (not) + V3.

$6.$ have not seen/ left

- S + have/ has + V3 since + Quá khứ đơn.

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$1.$ Money is collected by John. 

- S + is/ are + V (Pii) + (by O).

$2.$ The window was opened by Anna.

- S + was/ were + V (Pii) + (by O).

$3.$ Our homework has been done by us.

- S + have/ has + been + V (Pii) + (by O).

$4.$ A question will be asked by me.

- S + will + be + V (Pii) +(by O).

$5.$ The picture can be cut out by him.

- S + can + be + V (Pii) + (by O).

$6.$ Our rooms are cleaned by us.

- S + is/ are + V (Pii) + (by O).

$7.$ The car will not be repaired by William.

- S + will + be + V (Pii) +(by O).

$8.$ Was this circle drawn by Sue?

- Was/ Were + S + V (Pii) + (by O)?

$9.$ Could the dog be fed by you?

- Could + S + be + V (Pii) + (by O)?