避免棒材剪切时端部开裂，可通过（）来调节。
A.剪切时间
B.剪切温度
C.剪切长度
参考答案：B
She felt _____ of having asked such a silly question when the audience couldn't help laughing.
[ ]
A. guilty
B. crazy
C. miserable
D. ashamed
下列物质与水混合，在室温时难以形成饱和溶液的是 [ ]
A．CO2
B．H2SO4
C．C2H5OH
D．KNO3
