应急照明分配电装置的输出线路和集中控制型系统的控制线路选择燃烧性能为()级电线电缆时,应穿金属管保护。.
A.A
B.B1
C.B2
D.B3
参考答案:B
When it comes _________ ourselves at the weekend, he would talk about his fishing experiences in the countryside.
A.relaxing
B.to relax
C.to relaxing
D.being relaxed
A.能量不可以相互转化
B.自然界的能量是不守恒的
C.在利用能量的过程中有能量耗散
D.自然界中热现象的过程没有方向性