根据短文理解，从A、B、C、D四个选项中选择最佳答案填空。

    July 20th, 1969 was an important day. Two Americans 1 on the moon. Their 2 were Armstrong and Aldrin. They went there in a 3. Its name was ApolloⅡ.

    ApolloⅡ left the earth 4 July 16th and went three hundred and eighty-five thousand kilometers. It 5 the two Americans three days to get there. On July 20^th, the spaceship landed in the Sea of Tranquility (安静的世界). Armstrong 6 stepped onto (踏上) the moon. The two men walked on the surface of it. They 7 up some rocks and put them in the spaceship. They jumped up and down. They were 8 after their walk. So they had a rest.

    On July 21th, ApolloⅡleft the moon and 9 to the earth. Three days 10 it came down in the Pacific Ocean (太平洋). A ship took the men to America.

公民参与民主决策的前提和基础是（    ）

$\left(\frac{4}{15}+\frac{6}{25}\right)\times \frac{10}{19}$ =____

牛的运动系统的组成是（  ）

在综合素质评价中，小明作出了如下“自画像”，你认为他应该改进的是（）