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【单选题】Life of the Samoans①The Samoan islands are 2, 300 miles south of the Hawaiian islands. Though the land is steep, the islands have a plant cover watered by up to 200 inches of rain a year. All that rai...
A.
up to 200 inches
B.
mostly weed the land
C.
make the tree crops grow
D.
they are not eaten very often
E.
the Samoans do not work hard
F.
2.300 miles from the Hawaiian Islands
【单选题】关于精子和受精的描述，错误的是( )。
A.
精子和卵子一般是在输卵管内结合
B.
月经周期的中期，由于孕激素的作用，宫颈液变得稀薄，精子容易通过宫颈
C.
每次射精的精子数小于2 000万，即不容易使卵子受精
D.
人类和多数哺乳动物的精子必须在雌性生殖道内停留一段时间，才能获得使卵子受精的能力
E.
发生精子获能的主要部位是子宫腔，其次是输卵管