题目

23. –There were already five people in the car but they managed to take me as well.   --It _____ a comfortable journey. A.can’t be  B. shouldn’t be  C. mustn’t have been  D. couldn’t have been 答案：D“人类基因组计划”测定了人体细胞内的24条染色体，这24条染色体是 A．全部是常染色体            B．随机抽取的24条染色体 C．24对同源染色体的各一条    D．22对常染色体的各一条的X、Y染色体