题干

关于体内受精和早期胚胎培养的叙述,错误的是    (   )

A:排卵时,从卵泡内排出的是初级卵母细胞或次级卵母细胞

B:卵子完成受精的标志是卵黄膜和透明带间出现两个极体

C:卵黄膜封闭作用发生在精子接触卵黄膜时

D:卵子的发生是在雌性动物的卵巢内完成的

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答案(点此获取答案解析)

C

同类题3

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    In 1971 a young man who grew up very poor was travelling across the country, trying to make a new start for himself. Along the way he had completely run out of(用光) money and was forced to spend the night in his car. This continued until one morning, after a week of sleeping in his car, he walked nervously into a restaurant and ordered a big breakfast.

    After eating his first good meal in weeks, he found himself lying to the waiter, telling him he had lost his wallet. The waiter, who was also the owner, walked behind the chair where the young man had been sitting. He bent down, and came up with a $20 bill that looked as if it had fallen on the floor and said, “Son, you must have dropped this,” the owner said. The young man couldn't believe his luck! He quickly paid for the breakfast, left a tip, bought gas with the change, and headed West.

    On the way out of town, he began to understand what the owner did. Maybe nobody dropped the money at all. “Maybe that fellow just knew I was in trouble and he helped me in a way that didn't embarrass(使尴尬) me. So I just made a promise to help other people if I can.”

    Later, he worked very hard and became a rich man. Now he lives near Kansas City. Each year he gives away thousands of dollars. He is known as the “Secret Santa” because at Christmas time each year, he personally hands money out to those on the street and at restaurants. Last year, he gave more than $50,000 away in Kansas City.