`1.` A letter was being written to his friend by Peter.

`-` Mạo từ "a" đi với danh từ số ít `->` A letter là chủ ngữ số ít `=>` Đi với was

`2.` Some phone calls were being made by my friends.

`-` Some + N số nhiều `->` Chủ ngữ "Some phone calls" là chủ ngữ số nhiều `->` Đi với "were" 

`3.` Many accidents were being caused by bad drivers.

`-` Many + N số nhiều `->` Chủ ngữ "Many accidents" là chủ ngữ số nhiều `->` Đi với "were" 

`4.` That report was being prepared by Alex when I came to see him.

`-` Chủ ngữ "That report" - Bản báo cáo đó `-` Chỉ một sự vật `->` Chủ ngữ số ít `->` Đi với "was"

`-` "when I came to see him" là mệnh đề quá khứ đơn `-` Chỉ thời gian `->` đứng sau (by + O)

`5.` Her mother was being helped by Mary at that time.

`-` Chủ ngữ "Her mother" - Mẹ cô ấy `-` Chỉ một người `->` Chủ ngữ số ít `=>` Đi với "was" 

`-` Câu bị động thì QKTD:

`-` S + was/were + being + VpII + place + (by + O) + time. 

`-` BĐ `-` QKTD :

`=>` S + was / were + being + VpII ( by O )

`1`.A letter was being written to Peter's friend

`2`.Some phone calls were being made by my friends

`3`.Many accidents were being caused by bad drivers

`4`.That report was being prepared by Alex when I came to see him

`5`.Her mother was being helped by Mary at that time

`\text{# TF}`