题目

15℃时，声音在下列哪种介质中传播得最快     （ ）  A．空气          B．海水        C．钢             D．软木 答案： “Did you borrow the comic book from the library?”“ Yes. I _____ it for three days. I’ll return it this afternoon.A. borrowed B. keptC. have borrowed D. have kept