Walking alone in the dark the boy whistled to his courage.A. hold upB. keep upC. set upD.

问题补充：

Walking alone in the dark，the boy whistled to his courage.

A. hold up

B. keep up

C. set up

D. take up

答案：

A. hold up

(答案→)B. keep up

C. set up

D. take up

解析：考查动词短语辨析。句意：独自在黑暗中行走，男孩吹口哨保持勇气。B项意为“维持，不使低落”，符合句意。A项意为“举起”；C项意为“建立”；D项意为“拿起”。