把500g的水加热到100℃.需吸收1.68×105的热量.问水原来的温度是多少?——青夏教育精英家教网——

把500g的水加热到100℃，需吸收1.68×105的热量，问水原来的温度是多少？

甲、乙两种物质质量之比为4 : 3，放出热量之比为3 : 4，降低温度之比为9 : 8，则它们的比热容之比C甲：C乙为多少？

质量为800g，温度为-2℃的冰块放出8.4×103J热量后温度变为多高？［冰的比热容为　

关于声现象，下列说法正确的是　

A．物体不振动可能也会发出声音

B．声音在空气和水中的传播速度不同

C．减少噪声的唯一方法是不让物体发出噪声

D．“公共场所不要大声喧哗”是要求人们在公共场所说话音调放低些

人站在平面镜前，当他向平面镜走近时，发生的现象是

A．像变大，像到镜面的距离变小	B．像变大，像到镜面的距离变大
C．像不变，像到镜面的距离变小	D．像不变，像到镜面的距离不变

五.语法填空 (20分)
Dear Mr. Costa,
I’m sorry it has taken me so long to write. I’ve been very busy with work and school, but I’ve thought about you often.
How have you been (1)       (late)? Did you have a good Christmas and New Year’s? Mac says you’ve been working hard at (2)        restaurant and that business is very good. What else have you been doing?
I had a short (3)        good vacation. Mac and I went to Chicago for a few days before Christmas, but I had to come back and work (4)        Christmas and New Year’s, (5)       (include) Christmas Day and New Year’s Eve! Every time something like that (6)       (happen), I wonder (7)        I really want to work in the hotel business.
The other day I was thinking about the fun (8)        we used to have in our English class. I haven’t seen many of our classmates (9)        the course was over. In fact, the only one I see very often is Tomiko. I’d really like to get in touch with Franco. Does he ever write to you? If so, could you please send me his address?
Well, Mac and I are going skating and he is waiting for (10)       , so I guess I’d better say goodbye now. Write as soon as you can.
Yours ever

下列温度最接近23℃的是

A．人体的正常体温	B．北方冬季的平均气温
C．让人感觉温暖、舒适的房间温度	D．冰水混合物的温度

某机要室大门是由电动机控制的，钥匙(电路开关)分别由两名工作人员保管，单把钥匙无法打开。图1中符合要求的电路是

下列说法正确的是

A．换气扇和洗衣机的主要部件都是电动机

B．电热水器和电铃的主要部件都是电磁铁

C．磁卡和VCD播放用的光碟都是应用了磁性材料

D．地磁的南极在地理的南极附近

下列设备的运行与电磁波无关的是

A．医院里，医生利用B超可观察到母体内的婴儿情况

B．“嫦娥一号”接收地面指挥中心的运行指令实现变轨而奔向月球

C．汽车上安装有GPS（全球卫星定位系统）以确定行驶路线和距离

D．在大地震发生后救灾人员利用卫星电话恢复了与外界的通讯联系

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