when he was [ ] he went down to the small riverA.busyB.freeC.ill

问题描述:

when he was [ ] he went down to the small river
A.busy
B.free
C.ill

B

明显是B,free
只有空闲的才可以去河边玩。

答案是B
你要根据上下文来看:free在这里表示“空闲”
整句话的意思是:他空闲的话,才可以去河边玩