会议内容的控制主要包括对（）的控制。
A.会议目标
B.会议议题
C.会议时间
D.会议发言
参考答案：A, B, D
—It seems that Tom can't afford the house.
—Right. He wants to buy a _______ one.[ ]
A. more expensive
B. cheaper
C. very beautiful
D. more comfortable
氢气系统使用（）材料的阀门比较好。
A.铜或不锈钢
B.铸钢
C.生铁
