当变压器的本体、有载开关的重瓦斯保护投跳闸时，若需退出重瓦斯保护，则应预先制订安全措施，并限期恢复。
参考答案：对
___ no need for us to discuss the problem again. It has already been settled.
A．It has
B．There has
C．It is
D．There is
ISL G发动机额定功率范围为（）hp。
A、150-220
B、250-320
C、300-360
D、350-400
