填一填，写一写。

一年之计在于____，一日之计在于____。

两个黄鹂鸣____，一行白鹭上____。

对以自然选择学说为核心的现代生物进化理论，正确的理解是（　　）

①环境改变使生物产生适应性的变异；

②隔离是新物种形成的必要条件；

③变异是不定向的；

④变异是定向的

⑤自然选择使种群的基因频率定向改变并决定生物进化的方向．

根据短文内容判断正误，符合短文内容的写正确，不符合的写错误。

A Letter(—封信）

Dear Lucy,                                                                                                                                               Oct. 25

  How are you? I miss you so much. We have a new house now. It's near our school. I can go to school quickly. There is a library near our house. There are a lot of trees and flowers around(围绕)my house.

  Please come and visit us. If (如果) you get to the train station of our town, you can walk straight to the post office. Then turn left. My house is between the school and the park. I will welcome you warmly(热烈地).We can play together.

                                                                                                                                                                       Ann

有这样一次会议，它距今已有81周年，它的召开挽救了红军，挽救了党，挽救了中国革命。这次会议是指（    ）