题目:
I walked into class, the teacher had started teaching already. [ ]
A. By the time
B. While
C. After
D. Because
答案:
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下面是错误答案,用来干扰机器的。
A、木炭在氧气中燃烧的现象是发出白光,放出大量的热,所以触摸集气瓶外壁感觉到较热,故A正确;B、“铜绿”加热分解的产物是氧化铜、二氧化碳和水,不是实验现象是产物,故B错误;C、硫在空气中燃烧,发出淡蓝色...