黄叔叔家原来每月用水约10吨.更换了节水龙头后.每月用水约8吨,现在每月用水比原来节约了百分之几?
(10-8)÷10,
=2÷10,
=20%;
答:现在每月用水比原来节约了20%.
I'm sorry you ______ so long, but it' ll still be some time before Jim gets back.
A.wait
B.waited
C.had waited
D.have been waiting
A.a为动滑轮,B端钢缆受到滑轮组的拉力大小约为3G
B.a为动滑轮,B端钢缆受到滑轮组的拉力大小约为G
C.a、c为动滑轮,B端钢缆受到滑轮组的拉力大小约为3G
D.a、c为动滑轮,B端钢缆受到滑轮组的拉力大小约为G