【题目】He turned from side to side, eyeing himself in the mirror with a serious, studied ______ that soon changed into a smile.
A.impression
B.expression
C.conclusion
D.information

【答案】B
【解析】考查名词词义辨析。句意：他从一边转向另一边，看着镜子里的自己从严肃学究的表情瞬间变成了笑脸。A.impression 印象；B. expression表情，表达；C. conclusion总结； D. information信息；根据句意，故选B项。