受精完成的标志是 [ ]
A.雌、雄原核形成
B.精卵相遇,发生顶体反应
C.精子接触透明带
D.卵黄膜和透明带间出现两个极体
答案:D
He is ____ diligent pupil, but she is ___ diligent of all.
A.the most…the most
B.the most…a most
C.a most..the most
D.a most..a most
7845600读作______,改写成用“万”作单位的数是______.