线粒体和叶绿体都直接为细胞的生活提供动力。

Peter: Do you have a brother, John?

John: Yes, I do. His name is Mike.

Peter: Is he older than you?

John: No, he is younger than me. He is three years younger than me. He is 12 years old.

Peter: He is shorter than you, isn't he?

John: No, he is a little taller than me.

Peter: Are his eyes bigger than yours?

John: Yes, his eyes are bigger than mine.

Peter: Who loves sports more, you or your brother?

John: He does. He is good at playing football.

依次填入下面一段文字横线处的语句，衔接最恰当的一组是（   ）
这是一种有关写作态度的边缘试验。        ，        ，         。         ，         ，         。与笔端相比，我更看重脚步；与文章相比，我更关注生命；与精细相比，我更倾情糙粝。
①未及修改便已经传送出去发表     ②我早期的散文还有一点“做”的痕迹     ③没有资料可供查证，没有时间琢磨文句     ④容易碰擦到我已经离开的某些领域     ⑤这次终于可以用这种方式来表白了     ⑥比较彻底地阻断了“做学问”或“做文章”的任何企图

质量为m的汽车以V₀的速度安全驶过半径为R的凸形桥的桥顶，这时汽车对桥顶的压力是____，汽车能安全通过桥顶的最大行驶速度不能超过____（重力加速度为g）