西瓜(2n=22),无籽西瓜的体细胞染色体数目为()
参考答案:33
—You must have met him the other day.
—Oh, no, I ________.
A.hadn't
B.mustn't
C.haven't
D.didn't
恒河是南亚一条重要水源,主要灌溉区是[ ]
A、印度
B、阿富汗
C、老挝
D、伊朗