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问题 多项选择题

氧化铝磨料的特点是（）。

A．硬度高

B．耐久性好

C．使用寿命长

D．易产生较深划痕

答案

参考答案：A, B, C

补全对话，情景问答
补全对话。
A: Hi, mom! This is Mary. I need my pencils, English book and ruler.
    Can you bring them to me?
B:    1    Is your ruler in the drawer?
A: Yes, it is.
B:    2     Are they on the bookcase?
A:    3    They are on the table.
B: Where's your English book?
A:    4   
B: What color is it?
A:    5   
B: I find them.
A: Thank you.
A. No, they aren't.
B. It's blue.
C. Yes, I can.
D. Where are your pencils?
E. It's on the chair.
1._____ 2._____ 3._____ 4._____ 5._____
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选择题

酶是蛋白质因而具有蛋白质的特性，酶能催化许多有机化学反应。下图表示温度T(℃)与反应速度v关系的各曲线，有酶参加的是(　　)。
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