Tom ____ two tests tomorrow morning. [ ]
A. had
B. will have
C. has had
D. was having
答案:B
技术进步的经济意义直接表现为()。
A.改变了各产业的要素报酬率
B.产生一系列新兴产业
C.对资本和劳动的节约
D.产业结构调整
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