第29题: [单项选择]When something happens ______ we like, we usually feel joy or happiness, which is a positive and powerful emotion and for which we all strive. A. upon B. to C. that D. what 参考答案:C 答案解析:[注释] 空白后的we like是前面不定代词something的宾语,只能用that引导。
第30题: [单项选择]OSI模型分为几层() A. 4 B. 5 C. 6 D. 7 参考答案:D