题目

They tried to run away, but the police caught them                   .    A. at the end         B. in the end         C. by the end       D. to the end 答案：B某个基因的内含子中碱基A+T占40%，而外显子中A+T则占70%，已知由其中的一条链转录后拼接而成的一条RNA中U占25%，则该信使RNA中碱基A占A.15%B.25%C.45%D.75%