题目

完形填空（共20小题；每小题1.5分，满分30分）          阅读下面短文，掌握其大意，然后从36-55各题所给的四个选项（A、B、C和D）中选出最佳选项。 Life is filled with challenges. As we get older we ____36___ realize that those challenges are the very things that ____37___ us and make us who we are, it is the same with the challenges that come with ____38____. When we are faced with a challenge, we usually have two ____39____. We can try to beat it off, or we can decide that the thing ____40____ the challenge isn’t worth the ____41____ a单位换算：1kΩ=    Ω；1MΩ=    Ω．