Nobody but Jane and Tom _____ the news.[ ]
A. know
B. knows
C. have known
D. is known
答案:B
俄罗斯在世界上占有重要地位的产业是[ ]
A.核工业、宇航工业
B.农业
C.消费品制造业
D.防治、食品工业
安装截止阀跟安装闸阀一样,没有方向性。