什么是胀管工艺？
参考答案：
把管子插入要连接的管孔中，对管子进行冷态扩张，使管子与管孔间保持径向压力，实现两者紧密连接的冷作工艺过程。
Because of the nuclear crisis caused by the earthquake in Japan, many people lined up to buy salt ______ seeking protection from radiation.
A．in face of
B．in search of
C．in terms of
D．in hopes of
无菌包的有效期为多长时间
