安全阀在线校验时，先将阀体适当清洗、除绣，用肉眼检查安全阀阀体受压部分，如果有裂纹等缺陷应该（）。
参考答案：立即更换
—Are you free after school?
—Sorry: I’ve planned to treat a friend of mine to dinner for his help.
A．in terms
B．in honor
C．in turn
D．in return
-______ eraser is it on the desk?
-It's John's.[ ]
A. Who
B. What
C. Which
D. Whose
