题目

I regret ________ you all present that only one job will be offered in the department. A. telling           B. to tell    C. to have told            D. being told 答案：BXY型性别决定的生物，群体中的性别比例为1∶1，原因是（ ）A．雌配子数∶雄配子数=1∶1B．含X的卵细胞数∶含Y的精子数=1∶1C．含X的精子数∶含Y的精子数=1∶1D．含X的配子数∶含Y的配子数=1∶1