When people move to another country they often try the custom of their native land.A. to

问题补充：

When people move to another country, they often try the custom of their native land.

A. to keep on

B. to keep off

C. to keep up

D. to keep down

答案：

A. to keep on

B. to keep off

(答案→)C. to keep up

D. to keep down

解析：短语辨析。Keep on继续；keep off使…不接近；keep up保持，跟上；keep down控制，压制；句意：当人们搬到一个新的国家，他们总是努力跟上当地人的风俗习惯。故C正确。