何谓蠕变？
参考答案：
金属材料长期在高温环境和一定应力作用下工作，逐渐产生塑形变形的过程叫蠕变。
The house rent is increasing sharply nowadays. I’ve got about half the space I had five years ago but I am paying _______ now.
A．as five times much
B．as much five times
C．much as five times
D．five times as much
细粒中的人工砂是以岩石轧制而成的粒径在( )mm以下的石屑颗粒。
A．1
B．3
C．5
D．7
