抗冻系数Cf
参考答案：指岩样在±25℃的温度区间内，经多次“降温、冻结、升温、融解”循环后，岩样抗压强度下降量与冻融前的抗压强度的比值，用百分率表示。
根据提示补全句子。
1. Can I (use) your pen?
2. I (not) read a book yesterday.
3. My father____(like) hiking.
4. We (go) to Xi'an by plane last Sunday.
5. Where _____ you go on your holiday?
6. My bag is_____(big) than yours.
7. This ruler is _ ___(long) than that one.
8. I _____ (want) to buy a fan.
9. Lily_____(have) a bad cold yesterday.
10. I hope you will be_____(good) soon.
妥布霉素属（）类抗生素。
A、β-内酰胺类
B、大环内酯类
C、氨基苷类
D、四环素类
