He was overlooked when they choosing a new manager, which came as a complete surprise to

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A. set out
(答案→)B. set about
C. set off
D. set up
解析：句意: 选任新经理时没有考虑他，这完全出乎他的意料。set about 后接doing sth 表示 “着手；开始做某事”；而set out to do sth 开始做某事；set off出发；启程；引起；set up开办；设立；张贴；升起。