present perfect tense vs simple past tense

[aysaa]

Hello,

Teacher: Have you done your homework?
Student: Yes, I have ,but I didn't take it with me.

Can we use present perfect tense and simple past tense together like that?

Thank you...

[English Freak]

Sure.
Look at this one:
A: Have you ever been to Japan?
B: Yes, I have been there three times, but my last trip to Japan was really tiring. I just had to focus on my business.
And I'd prefer the student to say: "Yes, I have. But I don't have it with me." or "Yes, I have. But I forgot to take it with me."

[Raymott]

Hello,

Teacher: Have you done your homework?
Student: Yes, I have ,but I didn't take it with me.

Can we use present perfect tense and simple past tense together like that?

Thank you...

Of course. They are two separate events, and you use the appropriate tense for each.

[aysaa]

I think I have understood the difference between each other.

But we can't use them together as I wrote below.

One of my best friends named Jonny has moved to Japan ,but he came back here.

[emsr2d2]

I think I have understood the difference between each other.

But we can't use them together as I wrote below.

One of my best friends named Jonny has moved to Japan ,but he came back here.

You're right, that's incorrect.

One of my best friends, named Jonny, has moved to Japan = Jonny still lives in Japan.

One of my best friends, named Jonny, moved to Japan but he came back here = he moved to Japan at some point in the past but then he moved back here.

Concentrate on your placement of commas. Remember that the comma comes directly after a word, then there is a space, then the next word.