人的卵细胞比精子大得多,这是因为()
A.卵细胞含有更多的染色体
B.形成合子时卵细胞起主导作用
C.卵细胞为受精卵的发育贮存着营养物质
D.卵细胞中含有大量的遗传物质
参考答案:C
绦虫、姜片虫患者应选用的中药是()
A.贯众
B.槟榔
C.鹤草芽
D.南瓜子
E.苦楝皮
Although they had made careful preparation, unexpected difficulties ________ in the course of their
experiments. [ ]
A. rose
B. raised
C. lifted
D. arose