发酵工程的第一个重要工作是选择优良的单一纯种。消灭杂菌获得纯种的方法不包括（   ）

阅读下面的文字，按要求作文。

    落霞虽美，却是单调的，凭借孤鹜的齐飞，向人们展示了自己的美丽；孤鹜虽美，却是落寞的，凭借落霞的背景，成就了一幅灵动的画面。社会、人生又何尝不是如此？

    这段话引发了你哪些思考？请自选角度写一篇不少于800字的文章。

    要求：①立意自定，题目自拟，自选文体（诗歌除外）；②不要脱离材料的含意；③不得套作，不得抄袭；④用规范汉字书写。

某地一大宅院的灰墙上一幅墨字对联依稀可辩： “放开肚皮吃饱饭，鼓足干劲搞生产”，横批是“多快好省”。这幅对联最早应该书写于（   ）

   It' s Sunday morning. There are many people in the park, some boys are playing basketball. There are some girls under a big tree. They' re singing and dancing. What are those women doing? They are drinking tea. Look at the woman in a blue coat.  Who' s she?  She' s my mother. She is talking to Edward. Edward is her student. He is a good student. He studies hard . He' s good at all the subjects. And he' s friendly to all his teachers and his friends.