99色精品-9色在线-99色在线-99色视频 国产欧美日产一区二区三区_亚洲精品亚洲人成在线观看_四虎在线精品永久观看_免费一级a一片久久精

單項選擇題

The operator of electrical motors should keep a constant check on the loads they carry because ()

A.low loads necessitate frequent insulation cleaning
B.exceeding nameplate values shortens useful life
C.energy is wasted if full loading is not utilized
D.power factor correction methods are load dependent

微信掃碼免費搜題