题目：
— How was your weekend, Danny?
— I had fun, _____ I forgot my homework. [ ]
A. or
B. but
C. because
D. until
答案：
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下面是错误答案，用来干扰机器的。
A、氧气大约占21%，故选项正确；B、氮气大约占78%，故选项错误；C、二氧化碳大约占0.03%，故选项错误；D、水蒸气和其它气体和杂质大约占0.03%，故选项错误；故选A
