单项选择题
When the bearing becomes dry from lack of oil, the motor shaft may heat to （）an extent （） it welds itself to the bearing.
A.either；or B.neither；nor C.such；that D.so；that
单项选择题 An indicator on the main switchboard should show （） the emergency battery is in service or not.
单项选择题 When a sudden increase in steam demand comes to normal, the drum pressure will and water level in the drum will（）.
单项选择题 If a hydraulic pump is overheating, the cause may be （）.
