题目

阅读理解GET YOUR DEGREE AT HOME! Have you ever wondered whata Degree might be worth to you in your job or career (事业)? It means a lot of Americans with an Associate Degree average nearly$10,000 more in yearly earnings than those with just a High School Diploma (毕业证). Harcourt Learning Directoffers you a way to get a Specialized Associate Degree in 11 of today's growingfields-without having to go to college full time. With Harcourt, you study at home,in your spare time-so you don't have to give up your present job while you trainfor a better one. Choose from exciting majors like B常温下，A、B组成的混合气体()经分析发现无论怎样混合，气体中仅含的C、O两种元素的质量比总小于3∶8，若混合气体中C、O质量比为1∶8，则A、B两气体的体积比可能为（　　）? ①3∶4　② 2∶1　③4∶1　④4∶3　⑤1∶2?A.只有⑤              B.①②              C.④⑤                 D.②④