A、She has to accompany with her grandma. B、She has to prepare things for the picnic. C、She has a lot of housework to do. D、She h

W: Hi. Mike. How did your weekend go?
M: Fine. I went back to visit my grandma in the countryside.  
W: Lucky you. What did you do there?
M: I went for a walk in the hills with some of my friends.  
W: Was it good?
M: Yes. the scenery was amazing. The whole hillside was very red.  
W: How wonderful! Do anything else?
M: We went on a picnic on Sunday.  
W: Did you like it?
M: Very enjoyable. By the way, Lisa. what about your Weekend?
W: Don’t ask me. Mike.  
M: What happened?
W: I have got a cold. I could do nothing but lie in bed.  
M: Oh. dear.
Questions:  
What did Mike do last week?
Why did Lisa lie in bed and do nothing at weekend?