根据汉语提示，补全对话。

Chen: What are you going to do __________ __________ (这个周末)?

Sarah: I'm going to __________ __________ (植树).

Chen: __________ __________?

Sarah: Yes, I __________ (需要) some plants. So I'm going to the plant __________ (商店).

Chen: Are you going to use any books?

Sarah: Yes. I' m going to the __________ (书店).

交通标志支撑结构的安装应在混凝土强度达到设计要求后方可进行。