`Answer:`

`1,` A letter should have been sent to her since he moved to another city for good

`2,` Could the flowers be watered?

`3,` My motorbike may be repaired by my dad

`4,` A huge bunch of flowers will be given to me on my graduation day

`5,` Your homework must be done before coming to the class

`6,` A mysterious symbol on the ground in the basement might have been drawn by the cult to perform an unknown ritual

`7,` Helmets must be worn when joining the traffic

`8,` All the visitors’ belongings must be left behind before entering the playroom

`9,` Seatbelts must be worn by drivers and passengers

`10,` The tickets ought to be kept by passengers as they would be checked at the end of the ride by the staff

`11,` Books from the library can be borrowed by students for 2 weeks

`12,` This basket of food has to be brought to your grandma’s house before noon

`13,` May the chairs be returned to the hall after you have finished your conference, please?

`14,` This shirt must not be ironed under high heat

`15,` This tree doesn’t have to be watered regularly

___________________________________________________________

`@` Câu bị động với ĐTKT:

`+)` $\text{S + ĐTKT + be + VpII + by O...}$

`-)` $\text{S + ĐTKT + not + be + VpII + by O...}$

`?)` $\text{ĐTKT + (not) + S + be + VpII + by O...}$

`#TD`

`\color{#145277}{N}\color{#246483}{a}\color{#34768F} {e}\color{#44889B}{u}\color{#539AA7}{n}`

`***` Công thức câu bị động :

`@` Modal verbs : can, could, may, might, should, ought to, must, have to, will, would, be going to + be + V3/ed

`-` Thứ tự của Object : chốn `-` nhân (by O) `-` gian

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

`1.` A letter should have been sent to her since he moved to another city for good.

`2.` Could the flowers be watered `?`

`3.` My motorbike may be repaired by my dad.

`4.` A huge bunch of flowers will be given to me on my graduation day.

`5.` Your homework must be done before coming to the class.

`6.` A mysterious symbol on the ground in the basement might have been drawn by the cult to perform an unknown ritual.

`7.` Helmets must be worn when joining the traffic.

`8.` All the visitors’ belongings must be left behind before entering the playroom.

`9.` Seatbelts must be worn by drivers and passengers.

`10.` The tickets ought to be kept by passengers as they would be checked at the end of the ride by the staff.

`11.` Books from the library can be borrowed by students for `2` weeks.

`12.` This basket of food has to be brought to your grandma’s house before noon.

`13.` May the chairs be returned to the hall after you have finished your conference, please `?`

`14.` This shirt must not be ironed under high heat.

`15.` This tree doesn’t have to be watered regularly.