设a、b、c是△ABC的三边，化简：|a+b-c|+|a-c-b|+|b-c+a|．

在下列横线上填入适当的话语，使对话完整、正确。（共5小题，每小题3分，满分15分）

(It’s Friday today. Bob and Dave are talking about their weekend plans. )

Bob:  Dave, the radio says it is sunny tomorrow. Do you have any plans?

Dave:        76      . I want to go to the beach. What are you going to do?

Bob: I’m going to do some sports.

Dave:        77      ?

Bob: I like basketball best. I think it can help me grow taller.

Dave:        78      ?

Bob: I will play it in the gym. By the way, who will you go to the beach with?

Dave: I’ll go with my parents.

Bob:       79     ?

Dave: We will go there by car.

Bob: Have a good time.

Dave:       80      .