1.一般现在时:
I always swim in the afternoon.It is usually sunny.
He always swims in the afternoon.He feels very relaxed.
2.现在将来时:
I will swim tomorrow afternoon.I am not going to have any classes.
He will swim tomorrow afternoon.He is going to have a swimming test.
3.现在进行时:
I am swimming in the gym with my classmates now.I want to improve my swimming skill.
He is swimming in the gym with his classmates now.He likes swimming very much.
4.现在完成时:
I have already swum for nearly an hour. I enjoyed myself very much.
He has already swum for nearly an hour. He felt a little bit tired.
5.一般过去时:
I swam yesterday afternoon.I didn't do my homework.
He swam yesterday afternoon.He had nothing to do at that time.
6.过去将来时:
I told you just now that I would swim in the gym.You may find me there.
He said that he he would swim in the gym.And he asked us to meet him there.
7.过去进行时: 
She asked me if I was swimming in the lake.I said "yes".
He told us on the phone that he was swimming in the lake.And he wanted to continue.
8.过去完成时: 
I had already swum for half an hour when he came to the swimming pool.Then he joined us.
He told me that he had already swum for more than an hour.And he had never relaxed like that.
9.现在将来进行时: 
I will be swimming with my classmates tomorrow afternoon.I can't go to see my grandparents.
He will be swimming in the sea of Hawaii this time next year.I hope he will have a good time there.
10.现在完成进行时: 
I have been swimming here for thirty minutes.And more people are coming to join us.
He has been swimming here for an hour.It seems that he will be in the water for another hour.