$\frac{1}{3}$的倒数等于（　　）

    I used to go ____ with my mum on clear nights and look at the sky. It looked like black velvet with a million ____ on it. In different seasons, we saw different groups of stars. Sometimes we saw stars ____ brightly ____ the sky. How beautiful they were!

    Studying the stars was great ____ for me. Once I learnt a little about them, I soon wanted to find out more and more. Now it is my ____. I host a TV program ____ The Sky at Night. I use my knowledge to tell people about the stars in a ____ way. I am proud of my TV program me—it has ____ for more than 50 years!

在“探究弹性势能的表达式”的活动中为计算弹簧弹力所做功，把拉伸弹簧的过程分为很多小段，拉力在每小段可以认为是恒力，用各小段做功的代数和代表弹力在整个过程所做的功，物理学中把这种研究方法叫做“微元法”。下面实例中应用到这一思想方法的是（    ）

下面句中划线的成语运用不恰当的一项是（    ）