Please help me complete the questions below by giving assertive responses

Read the following scenario.
Just as you are about to go out the door for an important lunch meeting with a client, your boss calls you on the phone. She starts to tell you about the problem she has been having with a customer who has an issue that needs to be resolved. You’re anxious to get off the phone and go for lunch.
You say:

I’d like to hear more about it later. I was just on my way when you called. I’ll call you back as soon as I return from my lunch meeting. (Assertive)

Provide appropriate assertive responses for these situations:

1. Your boss begs you to work Friday night to complete a job. You are not scheduled to work and have already made plans. You say?

2. An employee at your work placement wants you to cover for her/him and tell the boss that she/he worked an afternoon shift they she didn’t work. You say?

3. One of your fellow employees at the placement is speaking to you and accusing another employee of lying. You do not agree. If you say nothing, you will feel that you are agreeing with the accuser and not being loyal to the victim. You say?