某电器商场，明知某冰箱有质量问题，但在销售时故意不加说明，顾客购买了有质量问题的冰箱，该行为属于 ()
A. 受欺诈的行为
B. 显失公平的行为
C. 行为人对行为内容有重大误解的行为
D. 乘人之危的行为
选择之债因有选择的一方行使了选择权而变为简单之债。 ()
A. 正确
B. 错误
张某和刘某夫妇无子女，后收养李某的幼子为养子。该养子 ()
A. 必须姓张
B. 必须姓刘
C. 必须姓李
D. 可以姓张，可以姓刘，可以姓李
Why was he employed by the firm？ ______.
A. Because he had worked in a computer shop.
Because he had learned to use computers at school.
C. Because he had worked very hard.
D. Because he had written some computer programs.
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