Mr Smith always goes for a walk with his dog when he is.A. busyB. freeC. healthD. alone

问题补充：

Mr Smith always goes for a walk with his dog when he is.

A. busy

B. free

C. health

D. alone

答案：

A. busy

(答案→)B. free

C. health

D. alone

解析：通过句中的always goes for a walk可知，史密斯先生应该是在不忙的时候才会去散步，故用free。Busy“繁忙的”，health“健康”，alone“单独地”。所以本题选B。