一般现在时：She always runs in the morning.
He seldom plays the computer games.
They have a picnic once a week.
正在进行时：Someone is singing a song.
She is doing her homework.
We are talking about the history of China.
一般过去时：They visited the museum last week.
I went to bed at 10:00 p.m.last night.
She gave a cup of tea to me.
现在完成时：Since then,she has never gone to work.
I have already done my homework.
She has been death.