东非各国是世界上最贫穷的地区之一，近年来部分国家为改善生活，正尝试利用国家公园发展旅游业。这些国家公园吸引游客的最主要条件为（ ）

句型转换。
(1) Why don't you play basketball with us?(同义句)
____  ____  play basketball with us ?
(2) There is something wrong with my computer. (同义句)
My computer  ____  ____ .
(3) My friend will arrive in four hours.（对划线部分提问）
____ ____ will your friend arrive?
(4) Does he go to the cinema every weekend?(用next week改写)
____ he____ to the cinema next week?
(5) We will have a sports meeting next week. (改为否定句)
We ____ ____  a sports meeting next week.   

对于密度公式ρ=$\frac{m}{V}$理解，下列说法正确的是（　　）