管道绝热的目的在于减少管内介质与外界的热传导，从而达到（）以及满足生产工艺要求等。
A、防泄漏
B、耐腐蚀
C、正常运行
D、节能、防冻
参考答案：D
is very clear to everyone that he's round and tall like a tree.
A．This
B．What
C．That
D．It
All the events of the Olympic Games were broadcast ___________ on TV. [ ]
A. alive
B. lively
C. live
D. living
