Q1) I'm sorry.

That's all right.
Think nothing of it.
It's nothing.
Not at all.
Think nothing of it.

Q2) Thank you.
You're welcome.
Don't mention it.
Not at all.
It's my pleasure.
It's nothing.

Are the answers to the two questions all correct?
Would you add some more suitable answers?

On the first set, "That's fine or That's O.K."

The expression "Not at all" is awkward in both sets.

Q1) The answers provided are all suitable and commonly used responses to someone apologizing. However, in addition to those, here are a few more responses you could use:

- No problem.
- It's okay.
- That's alright.
- No worries.
- It happens.

Q2) Similarly, the answers provided for expressing gratitude are suitable and widely used. Here are a few more responses you could consider:

- My pleasure.
- Anytime.
- You're very welcome.
- I'm glad I could help.
- No need to thank me.

It's worth noting that the choice of response may depend on the context and personal preference. Ultimately, the most important thing is to convey a genuine and warm response to the person expressing either an apology or gratitude.