用图甲所示的装置测出凸透镜的焦距，并“探究凸透镜成像规律”，当蜡烛、透镜、光屏位置如图乙时，在光屏上可成清晰的像．下列说法正确的是（　　）

如图所示，沿直径方向开有一凹槽的圆盘水平放置，可绕过中心O点的竖直轴转动，凹槽内有一根轻质弹簧，弹簧一端固定在O点，另一端连接质量为m的小滑块．弹簧的劲度系数为k、原长为l₀，圆盘半径为3l₀，槽底与小滑块间的动摩擦因数μ= $\frac{3k{l}_0}{5mg}$ ，凹槽侧面光滑．圆盘开始转动时，弹簧处于原长l₀．已知重力加速度为g，最大静摩擦力等于滑动摩擦力，弹簧始终在弹性限度内，则在圆盘转动过程中：

阅读下面短文，按照句子结构的语法性和上下文连贯的要求，在空格处填入一个适当的词或使用括号中词语的正确形式填空。      

       One morning，I was waiting at the bus stop，worried about____（be） late for school.There were many people waiting at the bus stop，____ some of them looked very anxious and____（disappoint）．When the bus finally came，we all hurried on board.I got a place next ____the window，so I had a good view of the sidewalk.A boy on a bike____（catch） my attention.He was riding beside the bus and waving his arms.I heard a passenger behind me shouting to the driver，but he refused ____（stop） until we reached the next stop.Still，the boy kept ____（ride）．He was carrying something over his shoulder and shouting.Finally，when we came to the next stop，the boy ran up to the door of the bus.I heard an excited conversation.Then the driver stood up and asked，“____ anyone lose a suitcase at the last stop？”A woman on the bus shouted，“Oh dear！It's ____（I）．”She pushed her way to the driver and took the suitcase thankfully.Everyone on the bus began talking about what the boy had done，and the crowd of strangers ____（sudden） became friendly to one another.

2015年3月12日，国务院总理***在《政府工作报告》指出，今后一个时期，着重解决好现有“三个1亿人”问题，促进1亿农业转移人口落户城镇，改造1亿人居住的城镇棚户区和城中村，引导1亿人在中西部地区就近城镇化。这要求社会主义和谐社会建设必须遵循        的要求。（     ）

①民主法治   ②公平正义   ③安定有序   ④人和自然和谐相处

①小玲取得的优异成绩正是她勤奋学习的结果。

②我们不能被困难吓倒。