阀门常用的连接形式有（）、（）、（）连接三种。阀门连接形式代号（）、（）表示内、外螺纹连接。
参考答案：螺纹；法兰；焊接；1；2
单词拼写
1. —Who is a _____ today?
—Dave. He is ill in bed, so he can't come here.
2. —Do you like Zhou Jielun or Liu Dehua?
—N______. I am not their fan.
3. Do you know when the Red Cross S_____ of China was founded (成立) ?
4. The important thing for us is to protect your ______(安全).
5. —How many people were ______ (到场的) at the meeting?
—More than 200.
在国际投资中，BOT项目合同安排中的基本合同或基石是（）。
A.建设合同
B.回购合同
C.特许协议
D.经营管理合同
