有關過去進行式問題一問

錯 應該是
When I was playing basketball in Apple Playground , Mary fell down .
or
Mary fell down when i was playing basketball in Apple play ground.

Your sentence is correct if you want to describe what you were doing when Mary fell on the floor of the playground.

If you want to describe what happened, or within what time period Mary fell on the floor, you could say: "Mary fell on the floor of the playground when I was playing basketball (from 9 am to 11 am).

Note that the main clause of your sentence is about "I", and the main clause of the alternative sentence above is "Mary".

Both versions are grammatically correct, the choice depends on what you would consider the main part, and the dependent part (the part following "when") of the sentence.

錯 應該是

I was playing basketball on Apple Playground at 9:00 to 11:00 this morning. When I
was playing basketball at ten forty-five,Mary fell on the floor of the Apple playground.

或者

I was playing basketball on Apple Playground at 9:00 to 11:00 this morning.Mary fell on the floor of the Apple playground when I was playing basketball at ten forty-five.

2014-10-26 13:02:18 補充：
我真係唔知你係想講"過去進行式"定係"過去式"

Kui,請補充