B

Slides (滑梯) are simple but always fun. All you need to do is to climb up to the top and slide down. But did you know that there is science behind this simple playground toy?
Isaac Newton (艾萨克·牛顿) said what goes up must come down. He was talking about gravity. Gravity is an invisible force (看不见的力量) that pulls everything down. Sliders work because of gravity, ① that is not all.
You climb up the slide ② sit down. You are ready to go. Are you sliding down? No. Not yet. Things stay still unless something makes them move. It is Newton’s first law, ③ you have to give yourself a push (推力) to start the journey down.
Now you are sliding down. Do you feel you are slowing down a bit? When two things rub (摩擦) against each other, they make friction. It is a force that works against the movement.
Without friction, you will slide down faster and faster to the bottom of the slide. It is dangerous, ④ that might be more fun.
At the bottom of the slide, you come to a full stop. Your feet touch the ground and add extra (额外的) friction. Newton’s first law also says moving things keep moving unless something makes them stop. So if you do not use your feet, you will fly off the slide and hurt yourself.

1. Which of the following can be put into No.1?
A. How fun a slider is!
B. How does science make a slide work?
C. How dangerous to slide down with a toy!
D. How fast can you slide down a slide?
2. Which of the following can be put into No.2?
A. jumping down from the high
B. walking on the ground
C. flying in the sky
D. throwing a basketball into a basket
3. Which of the following is the right order of the missing linking words (缺失连词)?
A. ①but ②and ③although ④so
B. ①and ②but ③although ④so
C. ①but ②and ③so ④although
D. ①and ②but ③so ④although
4. What can you infer from the passage?
A. Only heavy things can come down from the slide.
B. Slides mainly work because of the friction.
C. The water on the leaves will fall because of gravity.
D. Moving things keep moving because of gravity.

【文章大意】本文是一篇说明文，主要介绍了滑梯工作的科学原理。
1. B 主旨大意题。根据“But did you know that there is science behind this simple playground toy?”及表格的内容可知，本文主要介绍了滑梯工作的科学原理。故选 B。
2. B 推理判断题。根据“When two things rub against each other, they cause friction.”可知，当两种东西相互摩擦时，它们会产生摩擦力。B 选项“在地面上行走”可以产生摩擦力。故选 B。
3. C 推理判断题。根据“Sliders work because of gravity,... that is not all.”可知，滑梯因为重力而工作，但不是全部，前后是转折关系，用 but；根据“You climb up the slide... sit down.”可知，climb up the slide 与 sit down 两者是并列关系，用 and；根据“It is Newton's first law... you have to give yourself a push to start the journey down.”可知，这是牛顿的第一定律，所以你必须给自己一个推力，才能开始这段旅程。后部分是前部分的结果，用 so 连接；根据“It is dangerous... that might be more fun.”可知，这很危险，虽然可能更有趣，前后是让步关系，用 although 引导让步状语从句。因此正确的顺序是① but ② and ③ so ④ although。故选 C。
4. C 推理判断题。根据“Isaac Newton said what goes up must come down. He was talking about gravity. Gravity is an invisible force that pulls everything down.”可知，叶子上的水掉落是重力作用的结果。故选 C。

【分析】
这是一篇介绍滑梯背后科学原理的科普说明文，包含4道阅读理解题，分别考查主旨大意、推理判断、连词辨析、细节推理。解题时需结合上下文语境、文章主旨及相关物理常识，逐一分析每个选项的合理性，排除错误答案，选出符合文意的选项。
【解析】
1. 第1题：根据第一段最后一句“there is science behind this simple playground toy”及第二段围绕滑梯的科学原理展开的内容，可知本文主旨是介绍滑梯工作的科学原理，对应选项B。
2. 第2题：②处连接“climb up the slide”和“sit down”两个并列动作，结合选项，A跳下滑梯不符合安全逻辑，C飞在天空与爬滑梯无关，D投篮球和爬滑梯动作无关，B“在地面行走”可作为摩擦力的例子，且符合动作逻辑，故选B。
3. 第3题：①处前说滑梯因重力工作，后说“not all”，是转折关系，用but；②处爬滑梯和坐下是并列动作，用and；③处牛顿第一定律说明物体保持静止，所以需要推力启动，是因果关系，用so；④处危险和有趣是让步关系，用although，对应选项C。
4. 第4题：A选项“只有重的东西会下落”错误，重力对所有物体都适用；B选项“滑梯主要靠摩擦力工作”错误，主要靠重力；C选项“叶子上的水掉落是重力作用”符合牛顿重力定律，正确；D选项“运动的物体保持运动是因为重力”错误，是牛顿第一定律（惯性）的内容，故选C。
【答案】
1.B 2.B 3.C 4.C
【知识点】
阅读理解（主旨大意）、阅读理解（推理判断）、连词辨析、科普说明文阅读
【点评】
本文结合生活中的滑梯场景讲解物理知识，既考查学生的英语阅读理解能力，又渗透了基础物理常识，解题时需紧扣上下文语境，区分易混淆的物理概念，整体难度适中。
【难度系数】
0.5