转向架的主要功用是承担机车重量,产生并传递(),实现机车在线路上的行装。
A、横向力;
B、纵向力;
C、牵引力和制动力;
D、牵引力
参考答案:C
简述瓦尔拉斯“一般均衡理论”在其理论体系中的地位和指导思想。
E
If ______ , the family members were hungry.
A.Dick’s father could catch no fish in winter
B.Dick’s father had a boat in winter
C.Dick’s father had to look after him in winter
D.no food was sold in winter