2010年诺贝尔生理学或医学奖授予了试管婴儿之父——罗伯特·爱德华兹。在试管婴儿的培育过程中（   ）

①细胞分裂　②细胞分化　③细胞衰老　④细胞凋亡

语法填空

    In the past black people in South Africa ____(live) a miserable life. They could not vote to choose their ____(leader). They could not get jobs they wanted. The parts of town in which they had to live ____ (decide) by white people. They lived in the ____(poor) areas in the country and could not get jobs they wanted. Nelson Mandela, a modern hero, called black people ____ fight against white people to make black and white people equal. He said “We were put in a position ____we had either to accept we were less important,____ fight the Government. We chose to attack the law. We first broke the law____a way which was ____(peace); when this was not allowed…only then ____we decide to answer violence with violence.”

    We are learning English, but how can we learn English well? A student can know a lot about English, but maybe he can not speak English.
If you want to know how to swim, you must get into the river. And if you want to be a football player, you must play football. So , you see, you can learn English only by using it. You listen to your teacher carefully in class. You must read your lessons every day. You must speak English to your English teacher and classmates and also you must write in English. Then one day, you may find your English very good.

如图，将三个相同的三角板不重叠不留空隙地拼在一起，观察图形，在线段AB，BD，DE，EC，CA，AE中，相互平行的线段有（   ）

我国下列自然灾害中，最易在冬季发生的是（  ）