问题
选择题
工业上制石英玻璃和光导纤维的重要原料是 ( )
A．Al2O3
B．MgO
C．SiO2
D．Si
答案
答案：C
制石英玻璃和光导纤维的重要原料是SiO2，故选C。
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工业上制石英玻璃和光导纤维的重要原料是 ( )
A．Al2O3
B．MgO
C．SiO2
D．Si
答案：C
制石英玻璃和光导纤维的重要原料是SiO2，故选C。
| 阅读下面5段材料，从A到F选项中，找出与他们相对应的标题。 | |
| ( )1. Hello! My name is Sam. I am from Canada.. I like painting. My parents teach me Chinese. So I can speak a little Chinese. I want a Chinese pen friend. ( )2. In the future, Students will learn from their robot teachers. There will be no classrooms in schools. Students will play and study in gardens. Students will go to school only two or three times a week. ( )3. Do you like animals? I like them and I like pandas best. They are black and white. They eat bamboo and then sleep for about 12 hours a day. I think they are very lovely. ( )4. Do you have a pet (宠物) dog? I have one. Her name is Doudou. She has two big eyes and a small nose. She is very clever. She often plays games with me. ( )5. There is a library near my school. You can see many books there. I like science, so I like going there on weekends to read science books. There are always lots of people there.
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