在吊缸中发现活塞环搭口很光亮,其原因是()。
A.高温燃气漏泄
B.搭口间隙过大
C.搭口间隙过小
D.环失去弹性
参考答案:C
Pre-entry refers to the () of Customs entry documents for an export consignment before it actually leave the country.
A. report
B. submission
C. issue
D. order
直接埋地管道穿越铁路、公路时交角应不小于()。
A.30°
B.45°
C.60°
D.75°