题目

下列各句没有语病的一句是A.这套网上航班查询系统和民航总局计算机订座系统相连，具有及时、准确、信息全面等特点。B．人脑库的建立，标志着人类对脑科学的探索、对人脑生理和病理的研究进入了崭新的水平。C．高速磁悬浮列车在运行时与轨道完全不接触，列车的悬浮、导向、驱动和制动都靠的是利用电磁力来实现的。D．这个炼钢车间，由十天开一炉，变成五天开一炉，时间缩短了一倍。The manager was worried about the press conference his assistant ______ in his place but luckily, everything was going on smoothly. A．gave B．gives C．was giving D．had given