raining
It's raining hard.
雨下得很大。
rained
It rained hard, so I was late.
因为大雨所以我迟到了。
staying
I am just sitting and staying.
我只能坐着不动。
stayed
They stayed friends for years.
他们的友谊维持了多年。
studying
All of them are studying hard.
他们所有的人都学习努力。
studied
I studied maths at university.
我在大学里学的数学。
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