在液压试验中对于设计压力大于0.6MPa的天然气管道，应以( )为介质进行强度和严密性试验。
A．水
B．油
C．空气
D．天然气
参考答案：A
用所给词的适当形式填空。
1. I have a _____ busy week. (real)
2. Thanks for your _____ to visit next week. (invite)
3. Today is Tom's _____ birthday. (fourteen)
4. My _____ brother is two years _____ than me. (old)
泥浆护壁成孔灌注桩制备泥浆应选用（）
A.高塑性黏土
B.砂质土
C.水泥砂浆
D.砂质黏土
E.膨润土
