在石头上摩擦，划痕呈樱红色的药材是（）
A.雄黄
B.赭石
C.滑石
D.磁石
E.自然铜
参考答案：B
Write a passage of at least 50 words on the topic “ Trees are important”. ( 以“树是重要的”为题写一篇不少于50个词的短文，标点符号不占格。)
Use the following points as a reference.（以下问题仅供参考）
Why trees are important?(Give at least three reasons)
What would happen without trees?
How can we protect trees?
电压波动范围超过（）时，要停止潜水电泵的工作。
A.±3%
B.±5%
C.±8%
D.±10%
