[Grammar] The children were (doing/did/ had done) their homework when I got home.

[XomosX]

A. The children were doing their homework when I got home.
B. The children did their homework when I got home.
C. The children had done their homework when I got home.

A. She was cooking dinner when I got home.
B. She cooked dinner when I got home
C. She had cooked dinner when I got home

A. When Helen arrived, we were having dinner.
B. When Helen arrived, we had dinner.
B. When Helen arrived, we'd had dinner.

A. Sandra was standing under a tree when it begin to rain.
B. Sandra stood under a tree when it begin to rain.
C. Sandra had stood under a tree when it begin to rain.

Could you answer following questions:

1. Are the sentences above grammatically correct?
2. is there any difference in meaning between sentences "B" and "C"

 

[bhaisahab]

The first three groups are grammatical. The fourth requires "began" instead of "begin". In all cases there is a clear difference of meaning between sentences B. and C.

 

[XomosX]

Thank you for the answer.
In my native language there is only one past tense so I have difficulties with understanding the time frame difference.
I would translate "B" and "C" exactly the same into my native language.
Could you tell me what is the difference in meaning between sentences "B" and "C" ?
I would appreciate it if you could help me with that

 

[Matthew Wai]

B. The children did their homework when I got home.

The children started doing their homework immediately after I got home.

C. The children had done their homework when I got home.

The children had finished their homework before I got home.

Not a teacher.