TCM Ticket Checking Machine 是指什么？

The reason is ______ he is unable to operate the machine.

A:because B:why C:that D:whether

The price of this machine is not reasonable.

A:helpful B:kind C:fair D:effective

________ devices are interface of man and machine．

A:I/O B:Memory C:Disk D:Printer

Energy losses due to _____ occur in every machine.

A:speed B:friction C:impact D:atmosphere

To parallel an incoming machine to a running machine therefore it is necessary to ensure firstly that _____.

A:two frequencies must be brought into phase B:the incoming machine accepts a small amount of load C:the running machine must be unload D:both voltages are equal

HMI 的英文写法 human machine interface。（ ）