日本最著名的旅游胜地是（ ）

过椭圆C：$\left\{\begin{array}{c}x=2\cos \theta \\ y=\sqrt{3}\sin \theta \end{array}\right.$（θ为参数）的右焦点F作直线l交C于M，N两点，|MF|=m，|NF|=n，则$\frac{1}{m}$+$\frac{1}{n}$的值为（　　）

根据短文理解，从A、B、C、D四个选项中选择最佳答案填空。

    I have a cousin. 1 name is Eric. He is 2. He likes music and he can play 3 very well. But he 4 want to join the music club. He wants 5 the art club. He wants to learn 6. I don't like music 7 art, I like sports. I can play tennis. I can 8 swim but I can't swim 9. I want to join the sports club. My friends are in that club. I want to play sports with 10.

等质量的①CH₄、②H₂、③HCl、④SO₂，在标况下体积由大到小顺序是（    ）