目前，我国象棋男子棋手等级分排名最高的是？（）
A.许银川
B.洪智
C.吕钦
参考答案：B
David was responsible and hardworking, _____ he was promoted from a clerk to a manager.
A．which
B．as
C．for what
D．for which
干式变压器的冷却介质是（）。
A.空气
B.干粉
C.石英沙
D.二氧化碳
