宇宙空间资源的特点是 [ ]
A、空气薄、强辐射、失重
B、高真空、弱辐射、失重
C、高密度、强辐射、失重
D、高真空、强辐射、失重
答案：D
—What do you think of sports shows?
—______. [ ]
A. They are delicious
B. I love them
C. I like watching TV
D. I don't think so
空预器属于受热面旋转式还是风罩旋转式？
