属于中等强度作业（）
A．氧需不超过氧债
B．氧需几乎等于氧债
C．氧需超过氧债
D．氧需不超过氧上限
E．氧需超过氧上限
参考答案：D
We all feel it is Jack as well as his wife that ______ for their son’s bad performance at school.
A．are to blame
B．is to be blamed
C．are to be blamed
D．is to blame
中国移动通信集团公司成立于（）
