柯灵思英语-英语听力高手38

发表于:2018-12-07 / 阅读(33) / 评论(0) 分类 柯灵思英语

Why are there males and females? Why are there two sexes instead of three, or twelve, or one? On this Moment of Science we'll learn why two is the magic number. Let's start with why there is sex at all. When two organisms reproduce sexually, sperm an

发表于:2018-12-27 / 阅读(39) / 评论(0) 分类 英语听力广播—Listening

Egg Cells 卵细胞 Do you know what an egg cell is? 你知道什么是卵细胞吗? An egg cell is necessary for reproduction. 卵细胞是繁殖的必要条件。 Animals have egg cells. 动物有卵细胞。 Then does every animal have egg cells

发表于:2019-01-10 / 阅读(52) / 评论(0) 分类 与美国小学生一起学英文第10册

WASHINGTON, Aug. 4 (Xinhua) -- Researchers have found a way to turn mouse embryonic stem cells into sperm and this finding opens up new avenues for infertility research and treatment, according to astudy published Thursday in the online edition of jo

发表于:2019-02-04 / 阅读(123) / 评论(0) 分类 英语新闻

Our bodies are amazing. Although things go wrong at times, it's remarkable they work at all when one considers the complexities of their operation. Don and Ya?l present some awards to a few of the outstanding components. [APPLAUSE] D: Good evening, Y

发表于:2019-02-23 / 阅读(31) / 评论(0) 分类 英语时差8,16

In mammals, the sex of a baby is determined by the combination of chromosomes it inherits from its parents. Nearly every cell in a male body has two different sex chromosomesone is shaped like an X and one is shaped like a Y. Females also have two se

发表于:2019-03-06 / 阅读(93) / 评论(0) 分类 英语时差8,16