阀门在使用中常见的问题有（）、（）、（）、（）和（）等。
参考答案：泄漏；腐蚀；擦伤；振动；噪声
In English class, our teacher often creates an environment _____________ we are given the opportunity to solve problems ourselves.
A．when
B．which
C．where
D．that
I can't leave. She told me that I ____ stay here until she comes back. [ ]
A. may
B. must
C. can
D. will
