问题补充：
He tried hard to keep calm in face of the policemen, but the sweat on his forehead .
A. turned him down
B. gave him away
C. showed him out
D. shut him off
答案：
A. turned him down
(答案→)B. gave him away
C. showed him out
D. shut him off
解析：本题考查动词短语辨析。句意：面对警察，他努力保持冷静，但他额头上的汗让他露出了马脚。give away出卖。turn down拒绝；show out送出（客人）shut off关掉，与shut down意思相近。
