Chemicals in the body our food into useful thingsA. break intoB. break upC. break dow

问题补充：

Chemicals in the body our food into useful things．

A. break, into

B. break, up

C. break, down

D. break, off

答案：

A. break, into

B. break, up

(答案→)C. break, down

D. break, off

解析：考查短语辨析。break into 破门而入，break up 解散，break down 分解，break off 中断，句意：身体中的化学物质把我们的食物分解成有用的东西。所以选C。