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.”

一个两位数，个位和十位数学都是质数，个位与十位数字的积是21，这个数是____。

血液通过肺循环后，其成分的变化主要是（    ）

读“中东地区简图”，回答下列问题。