为了调节吸风点的风量，在吸风罩的联接支管上要设置（）。
参考答案：调节阀
We all feel it is Jack as well as his wife that ____ for their son's bad behaviour at school. [ ]
A. are to blame
B. is to be blamed
C. are to be blamed
D. is to blame
假如失去重力，将会出现什么样子的现象？展开想像，说出两个合理的场景．
答：______．
