夏季，为了给密闭的洗相暗室降温，从降温效果看较好的方法是（ ）
A．打开电扇
B．打开冰箱冷冻室的门
C．用盆子装几大块冰
D．地上洒水
A、打开电扇，虽然能加速了空气流动，加快了蒸发．但由于洗相暗室是密闭的，空气流动不好、温度下降较慢；同时，由于开了电扇，形成的风会使相片吹散，方法不好．
B、在冰箱制冷的同时，冰箱的压缩机也在散热．冰箱仅仅是把冰箱里的热能转换到冰箱外面而已．根据能量守恒，冰箱的制冷应该是和其他设备的散热等价．那么室内温度应该不变．但是我们还为电冰箱提供了电能，这部分额外的能量最终也必须以各种形式最终释放出来，很大一部分都是以热能的形式释放的．所以夏天打开冰箱降温实际上会使室内温度升高．方法不好．
C、用盆子装几大块冰，冰会吸收空气中的热，使温度降低．方法较好
D、地上洒水，由于相室内空气不流动，水蒸发较慢．方法不好．
故选C．
阅读短文，根据内容判断正误。正确的选“A”，错误的选“B” Blogs (博客) are the place where young people go to reveal(释放) their souls（灵魂）. Many people enjoy the freedom in blogging. Some, however, find that putting one’s life online can have a price. Some students in America got suspensions (暂停) because on their blogs they posted threatening words to their teachers. Recent surveys found that nearly one fifth of teens who have access to the Web have their own blogs. And 38% of teens say they read other people’s blogs. By comparison, about a tenth of adults have their own blogs and a quarter say they read other people’s online journals. With the development of the Internet, more and more people will be engaged in blogging. In another survey, 79% of teens agreed that people at their age aren’t careful enough when giving out information about themselves online. Besides, careless blogging can also affect blog viewers. When you are angry or frustrated, your blog is the first place you turn to. The words you post then may not be rational which you may regret(后悔) later. To reduce the negative effect, change the permission setting and make such posts “private” so that only you can read them. As long as you are careful with what you post, blogging is a great means of staying in touch with friends and displaying one’s creative works. 小题1: Blogs are the place where people go online to express themselves freely. 小题2: The fact that some American students got suspensions is used to show that people should not put their life online.
小题5: Recent surveys found that over 50％ of teens who have access to the Web have their own blogs. |