OTDR主要功能有：测量光缆的长度、（）和光纤的后向散射曲线。
A.光纤损耗
B.反射损耗
C.测量光纤的插去损耗
D.回损
参考答案：A, B, C, D
具行气安胎作用的药物是（）、砂仁。
用所给词的适当形式填空。
1. The boys in my class are ______(cautious) not to make any mistakes in spelling than ever before.
2. I am ________(negative) that you took down my number incorrectly.
3. He has a real ________(enthusiastic) for teaching.
4. She noticed a sudden _______(move) behind the tree.
5. They discussed the situation _________(private) .
6. Scientists disagree about how the universe________(creative).
7. Such problems are a______(universe) feature of all ages.
8. I suddenly lost my balance and fell _______(forward) .
