风机、水泵采用节能型变频器进行节电改造,能够取得更好的节电效果,与调节阀门、挡板相比,可节能()。
A.15-20%;
B.25-30;
C.40-50;
D.50-60
参考答案:C
When Jim was a child, they ______ to France. [ ]
A. lived
B. worked
C. reached
D. moved
上部转台与下机架通过中央枢轴,组成()联接。