用400L自落式搅拌机搅拌坍落度为30mm的混凝土其搅拌的最短时间为()。
A．60s
B．90s
C．120s
D．150s
参考答案：C
读一读，补全对话。
Mike : 1._______________________ ?
Chen: My birthday is in September.
Mike: 2.________________________ ?
Chen: It's September 11th.
Mike: 3.___________________________?
Chen: Yes, my birthday is in fall.
Mike: 4.__________________________ ?
Chen: It's windy and cool.
Mike: 5.__________________________?
Chen: Yes, I like winter. But my favourite season is summer.
茴香散2功效与作用
