我国产量居世界第一位的农产品是[ ]
A、棉花、油菜子、花生
B、水果、玉米、稻米
C、大豆、小麦、肉类
D、粮良、小麦、玉米
答案：A
--- Are your family ready for rafting?
---Yes, I really want my children to experience that they are young
A．\
B．while
C．unless
D．if
横管冷却器内煤气由（）向（）流动，冷却水由（）向（）流动，煤气与冷却水逆向流动。
