在装配平键时，键安装于轴的键槽中，必须与槽底（  ）。 A.
接触 B.
不接触 C.
间隙不要过大 D.
垫铜片

A．the consumer can rank all possible consumption bundles.
B．all preferences conditions are met.
C．the consumers can rank all affordable consumption bundles.
D．more of a good is always better.