`1.` The accident was caused in this city by some drunk drivers.

`-` Bị động thì QKĐ: S + was/were + Vpp + (by + O)

`-` CN là 'the accident ...' số ít `->` Dùng 'was'

`2.` Their friends were met at the railway station by a groups of students.

`-` CN là 'their friends ...' số nhiều `->` Dùng 'were'

`-` Trạng từ chỉ nơi chốn đứng trước 'by + O', trạng từ chỉ thời gian đứng sau 'by + O'

`3.` A great deal of tea is drunk in England.

`-` Bị động thì HTĐ: S + is/am/are + Vpp + (by + O)

`-` CN là 'a great deal of tea' số ít `->` Dùng 'is'

`-` Các từ bất định như 'people' trong câu, hay đại từ bất định (everyone, someone, v.v.) không dùng 'by + O'

Bị động:

 - QKD: S + was/were + V3/ed 

- HTD: S + am/is/are + V3/ed 

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1. The accident was caused in this city by some drunk drivers.

2. A group of students' friends were met at the railway station. 

3. A great deal of tea is drunk in England.

2. A group of students' friends were met at the railway station.