钻井泵上的泵压表所显示的压力值是（）。
A.绝对压力
B.相对压力
C.绝对压力加大气压
D.相对压力减大气压
参考答案：B
根据句意及首字母提示补全单词。
1. We've been doing experiments for 24 hours without a b_____.
2. F_____ , they caught the last bus last night.
3. Hosting the World Expo successfully was great e_____ in Chinese history.
4. Do you know when the Red Cross S_____ of China was founded?
5. Heroin (海洛因) is a kind of hard d_____.
6. All the students are present, nobody is a_____.
导线为什么要换位？
