cau chu dong ==> bi dong
1. has Tom finished the work?
2. i have bought this teddy bear in that shop
3. we have finished the report
4. i have done my exercise for three days

`1` .has the work been finished by Tom `?` 

`->` the work là chủ ngữ số ít `->` dùng has 

`2` .This teddy bear has been bought in that shop by me

`->` this teddy bear là chủ ngữ số ít `->` dùng has 

`->` buy(v1) `->` bought(v2) `->` bought(v3)

`3` .The report has been finished by us

`->` the report là chủ ngữ số ít `->` dùng has

`4` .My exercise has been done for three days

`->` my exercise là chủ ngữ số ít `->` dùng has

`->` for `+` khoảng thời gian `->` HTHT

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`=>` cấu trúc hiện tại hoàn thành : `(+)` S `+` have/has `+` V3/-ed 

`=>` bị động hiện tại hoàn thành : Have/has `+` S `+` been `+` V3/-ed `+` ( by s.o) 

Giải thích:

`-` Câu bị động HTHT:

`(+)` S `+` have/has `+` been `+` V3/V-ed..(by `+` O) 

`(-)` S `+` haven't/hasn't `+` been `+` V3/V-ed..(by `+` O) 

`(?)` Have/Has `+` S `+` been `+` V3/V-ed ... (by `+` O) ? 

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`1,` Has the work been finished by Tom?

`2,` This teddy bear has been bought in that shop.

`3,` The report has been finished.

`4,` My exercise has been done for three days.