— Hi, what did our monitor say just now?

— Every boy and every girl as well as teachers who are to visit Water Cube ______ asked to be at school gate before 6∶30 tomorrow morning.

A．is　　　

B．were

C．are　　　

D．was

表面应力、应变曲线中直线段的斜率为（）

A.正弹性摸量

B.剪切切弹性摸量

C.屈服应力