`1.` The lost child has just been found behind the supermarket by the police.

`->` Bị động HTHT (`+`) : S + have/has + been PII (by O)

`->` The lost child là N số ít, dùng Has

`2.` We have never eaten these dishes before.

`->` This is the first time + S + have/has + (ever) + PII

`=` S + have/has + not/never + PII + before.

`color{red}{#lgdr}`

`1` The lost child has just been found behind the supermarket by the police .

`-` Bị động hiện tại hoàn thành : S(bị động) + have/has + been + V3/Vpp + O .

`2` We have never eaten these dishes before .

`-` S + have/has + never + V3/Vpp + before : Ai đó chưa bao giờ làm gì trước đó .