从下面方框中选择适当的词填入短文中，使短文通顺正确（注意有些词要用适当的形式）。

    One day, Mr. White told the class to get ready for a hobby show. The students ____  the whole morning getting what they were going to show.
     All the students came back on time but Bob, the laziest ____ in his classmates' eyes. It seemed that it was very ____  for Bob to have a hobby. But to their surprise, Bob came back with many ____ stamps in his hand. Mr. White was very happy after watching them. However, Bob was going to ____ them back.
“Bob, you can't take them back until the others watch them this afternoon,” said Mr. White.
“But I am sorry they are my brother’'s,” he answered. “He doesn't want them to be out of our home for long. He's afraid that they will be ____  .”
“Bob, you should show some of your own ____  here, not someone else's. Mr. White became kind of angry.
But Bob's words made him even ____ . “Mr. White, it's true that I have a hobby. My hobby is watching my brother collecting stamps.”

一客车从静止开始以加速度a作匀加速直线运动的同时，在车尾的后面离车头为s远的地方有一乘客以某一恒定速度正在追赶这列客车，已知司机从车头反光镜内能看到离车头的最远距离为s₀（即人离车头距离超过s₀，司机不能从反光镜中看到该人），同时司机从反光镜中看到该人的像必须持续时间在t₀内才能会注意到该人，这样才能制动客车使车停下来，该乘客要想乘坐上这列客车，追赶客车匀速运动的速度v所满足条件的表达式是什么？若a=1.0m/s²，s=30m，s₀=20m，t₀=4.0s，求v的最小值．