Why don't we talk about it over lunch?
Is there anything I can do to help?
I don't think that's right.
I have no idea what you are talking about.
Do you want me to stay late and finish?
How many copies did you say you needed?
I'm sorry; I don't quite understand what you are saying.
You have given me too much work. I need more time.
I can't understand what you mean.
I'm afraid I see things differently.
I'm very sorry. I have had a lot of problems lately. I'll be on time from now on.
I guess I could stay late and finish up.
Now tell me again; how many copies was that?
Do you want me to stay late and finish?
I'm afraid I won't be able to finish all of this work on time.
Let's talk about it over lunch, ok?
That was thirty copies, right?
I'm sorry about your brother.
I'm sorry that you are having problems at home; so just try to do the best you can here.
Is there anything I can do to help?
Maybe we could talk about it over lunch.
There are a lot of people who don't show up on time. Why are you picking on me?
I omitted "that" in this sentence:
I'm sorry that you are having problems at home; so just try to do the best you can here.
If "that" isn't needed for the sentence to grammatically make sense, you don't need to use it. The overuse of "that" is a very common mistake, even by native speakers.