When you meet some trouble about how to use this new kind of machine you can the instruct

问题补充：

When you meet some trouble about how to use this new kind of machine,

you can the instruction.

A. look for

B. see

C. refer to

D. check

答案：

A. look for

B. see

(答案→)C. refer to

D. check

解析：可联系答.案.网客服索取。