细菌的生殖方式和主要营养方式分别为（ ）

阅读下列材料，从各题所给的A.B.C.D.四个选项中，选出一个最佳答案。

Dear Jenny,

I am in Beijing, China now, but my parents are in the USA. I live with my broth er Peter. Beijing is big and great. There are many beautiful places and much delicious food here. I like Beijing very much.

    Peter and I are in the same grade, but we are in different classes. We live far from the school and it takes us a long time to go to school. We have to get up at 6:20 in the morning, and then at 6:30 we ride bikes to the bus stop. It takes us about 20 minutes. At about 7:00, we take the bus to school. We get to school at about 7:30.

    We have four classes in the morning and two in the afternoon. I think Chinese is too difficult, but Peter thinks it is easy. He can speak Chinese very well and he often helps me with it.

    How is everything going with you in the USA? Write to me soon.

Love,

Kate

⊙O的半径为2，点P是⊙O外一点，OP的长为3，那么以P为圆心，且与⊙O相切的圆的半径一定是(       )

在下面一段文字横线处补写恰当的语句，使整段文字语意完整连贯，内容贴切，逻辑严密。每处不超过15个字。

    核电有零排放的环保优势，①____。在选择支持核电之前，一位环保人士如此纠结。其实，在人类历史的进程中，②____？汽车与车祸、飞机与空难、摩天大楼与熊熊大火……科技发展提供了便捷，也带来了风险。发展中不同诉求交织、冲突，③____。如何在面临两难时做出权衡，在面对风险时保持理性，在全力提高安全性、可靠性的前提下大力利用新技术，这是我们不得不面对的课题。也正是在与这种“宿命”抗争的过程中，不因噎废食，不一劳永逸，人类才不断创造着新文明，实现着更加全面自由的发展。