The Australian boy has a good of Chinese and can express himself freely in it.A. demandB.

问题补充：

The Australian boy has a good of Chinese and can express himself freely in it.

A. demand

B. power

C. command

D. usage

答案：

A. demand

B. power

(答案→)C. command

D. usage

解析：考查固定词组。固定词组have a command of掌握…；句意：那个澳大利亚的男孩掌握了中文，能够用中文流利地表达自己。故C正确。