高速铁路正线应采用()无缝线路,到发线应采用无缝线路。无缝线路应具有足够的强度和稳定性。
参考答案:跨区间
When I talked with my grandma on the phone, she sounded weak, but by the time we ____ up, he voice had been full of life.
A.were hanging
B.had hung
C.hung
D.would hang
循环冷却水的沉积物控制中,沉积物控制包括______,而黏垢控制往往与微生物控制分不开。
A.结垢控制
B.污垢控制
C.腐蚀控制
D.水中离子控制