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在下列数- ,+1,6.7,-14,0, , -5 ,25% 中,属于整数的有(    )
A . 2个 B . 3个 C . 4个 D . 5个
火车在长直的轨道上匀速行驶,门窗紧闭的车厢内有一人向上跳起,发现仍落回到原处,这是因为(  )
A . 人跳起后直到落地,在水平方向上人和车始终具有相同的速度 B . 人跳起的瞬间,车厢的地板给人一个向前的力,推动他随火车一起运动 C . 人跳起后,车继续前进,所以人落下必然偏后一些,只是由于时间很短,偏后的距离不易观察出来 D . 人跳起后,车厢内空气给他以向前的力,带着他随火车一起向前运动
方程2x﹣1=0的解是x=
如图,△ABO三个顶点的坐标分别为A(2,4),B(6,0),O(0,0),以原点O为位似中心,把这个三角形缩小为原来的 ,可以得到△A′B′O,已知点B′的坐标是(3,0),则点A′的坐标是

如图甲所示是某一学习小组探究“斜面的机械效率”实验装置.小名猜想斜面的机械效率可能跟斜面的粗糙程度有关,小悦猜想斜面的机械效率可能跟斜面的倾斜程度有关.表格是其中一位同学在其它条件一定时的实验数据.

  1. (1) 实验时,沿斜面拉动木块时,为使测力计的示数稳定,应尽量使木块做运动.
  2. (2) 通过比较表格中“物块重”和“”两栏对应的数据,可知斜面是一种省力的简单机械.

    实验

    次数

    斜面的倾

    斜程度

    物块重

    力G/N

    斜面高

    度h/m

    拉力

    F/N

    斜面长

    度S/m

    机械效

    率η

    1

    较缓

    10

    0.2

    5.5

    1

    36.4%

    2

    较陡

    10

    0.4

    7.0

    1

    57.1%

    3

    最陡

    10

    0.6

    8.5

    1

    70.6%

  3. (3) 表格实验数据验证了(小名/小悦)的猜想,结论是:在其它条件一定时,斜面,机械效率越高.
  4. (4) 第一次实验中,物块所受斜面的摩擦力为N.
  5. (5) 请你进一步分析了实验数据,并结合所学物理知识,解决下列关于斜面的物理问题.图乙中斜面1的长度小于斜面2的长度,木块从斜面顶端由静止释放后沿着斜面下滑,该过程中斜面对木块的支持力(做功/不做功).木块到达斜面1、2底端时的速度分别为v1、v2 , 若斜面光滑,则v1v2(大于/小于/等于);若斜面粗糙程度相同,则v1v2(大于/小于/等于).
下面是四(1)班同学几项体育项目成绩达标人数统计表

  1. (1) 根据以上数据完成下面的复式统计图并回答问题.

  2. (2) 项目男生达标人数最多,项目女生达标的人数最多.
  3. (3) 全班达标人数最少的项目是
  4. (4) 请你再提出一个数学问题并解答.
                         
  1. (1) 1只小兔拔2个萝卜,7只小兔拔多少个萝卜?

    加法算式:

    乘法算式:

    口答:7只小兔拔()个萝卜。

  2. (2) 超市的玻璃杯,每盒有4个,有6盒。?(提出一个问题并列式解答)

    列式:

    口答:一共有()个杯子。

  3. (3) 张阿姨买了4盒奶和一个皮球,一共需要多少元?

    列式:

    口答:一共需要()元。

A . I like eating bread. B . I like eating meat. C . I like eating fish.
已知3sinβ=sin(2α+β),求证:tan(α+β)=2tanα.

中华文化的精髓是(    )

A . 中华语言文字 B . 中华文化典籍 C . 中华科技工艺 D . 中华传统美德
按下列要求,写出电子数相同的两种不同粒子的化学符号.

  1. (1) 两种不同的离子

  2. (2) 一种原子和一种分子

为检验某制剂对机体免疫机能的调节作用,用含不同剂量该制剂的饲料饲喂健康小鼠,一段时间后给小鼠注射绵羊红细胞,测定小鼠血清中溶血素(针对绵羊红细胞的抗体,能导致其溶解)的含量得到下图结果。下列判断不正确的是(  )

A . 实验中用到的绵羊红细胞相当于抗原 B . 中剂量的该制剂对小鼠免疫机能的增强作用最大 C . 溶血素能导致绵羊红细胞溶解,这个过程属于细胞免疫 D . 溶血素由浆细胞合成,其分泌过程依赖于细胞膜的流动性
在正方形的空格里填上适当的数,使每一横行、竖行、斜行的三个数相加的和都等于指定的数。


阅读理解

    Jehdi and Hassan were businessmen and good friends.

    One day they found themselves in a forest. They were tired so they sat down and Jehdi fell asleep.

    As Jehdi slept, Hassan saw a wasp (黄蜂) coming from his friend's nose. It flew toward a pine tree (松树), circled it three times, and then returned to Jehdi's nose.

    When Jehdi woke he said, “Hassan, What a dream! Imagine a big pine tree, like that one there. A wasp flies around it and its buzz (嗡嗡叫) seems to say,

    ‘You must dig here.' I dig and I find a big box of gold.”

    “Yes, a strange dream,” replied Hassan. “Why don't you dig around that tree and see if it's true?”

    “My friend, it was just a dream and anyway it's too hot to dig.”

    Hassan said, “If you do not want to dig, I will. Sell your dream to me.”

    “How much will you pay?” asked Jehdi.

    Hassan agreed to pay 300 coins.

    “Never have I made such a business deal. How naïve (天真的) you are, Hassan!”

    The two friends then went to the pine tree Jehdi had dreamed about. Jehdi stood there with a smile on his face to see Hassan start digging. But he laughed on the other side of his face when Hassan dug up a huge box of gold.

    After this, Hassan had so much gold that he lived a rich life until his death. Jehdi often visited him. He would say, “Well, Hassan, how are you? I have come to see my dream.” They would pat(轻拍) each other on the back and laugh. But each time Jehdi went home sadly. He could never buy back his dream.

  1. (1) In Jehdi's dream, he ________.
    A . is attacked by a wasp B . digs up a box of gold C . talks with a wasp D . becomes a wasp himself
  2. (2) Jehdi is not willing to dig because_________.
    A . he doesn't believe his dream is true B . he is lazy and doesn't want to work C . he is too rich to care about the gold D . he can't find the tree from his dream
  3. (3) Jehdi thinks Hassan is _____ to agree to the deal.
    A . smart B . wise C . stupid D . kind
  4. (4) The phrase “laughed on the other side of his face” probably means___________.
    A . was unhappy about something one was once happy about B . was excited at something one was once disappointed by C . laughed so much that one's face change D . laughed at other people's mistake
“我不喜欢爸爸妈妈干涉我的事情。可是,当我遇到麻烦时,还是渴望爸爸妈妈出现”。这种矛盾心理主要表现为(    )
A . 反抗与依赖 B . 闭锁与开放 C . 勇敢与怯懦 D . 自我意识强
何大妈在气温达到40.4℃时,没开空调的屋子里熬了两天,送到医院时体温高达41.7℃,却一点汗也没有,患“热射病”致使多个脏器衰竭,生命垂危。下列关于体温调节的说法正确的是(  )
A . 何大妈产热的主要部分是骨骼肌 B . 何大妈体内产生的热量大于散出的热量,导致体温上升 C . 正常情况下,在高温环境中血管收缩,汗液分泌增加 D . 体温调节中枢在大脑部位
下列表示正确的是(   )
A . B . C . D .
在抗击新冠疫情过程中,某市采用无人机对各县区的主要道路、路口进行了巡查。无人机在匀速下降的过程中(   )

A . 动能变大 B . 动能不变 C . 势能变大 D . 机械能不变
面对突如其来的新型冠状病毒,越来越多人意识到口罩和医用酒精的重要作用,医用口罩由三层无纺布制成,无纺布的主要原料是聚丙烯树脂。下列说法错误的是(   )
A . 医用口罩能有效预防新型冠状病毒传染 B . 聚丙烯树脂属于合成有机高分子材料 C . 医用酒精中乙醇的体积分数为95% D . 抗病毒疫苗冷藏存放的目的是避免蛋白质变性
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