题型：问答题 简答题 阅读短文，从下列方框中，选择正确的单词并用其适当的形式填空。do enough hour also take In China, more and more middle school students are getting shorter sleeping time than before. Most students sleep less than nine _____ every night because they have much homework _____. Some homework is given by their teachers, and some by their parents. _____, some students don't know how to save time. They are not careful _____ while they do their homework, so it _____ them a lot of time. Some students spend too much time watching TV programmes or playing computer games. They stay up very late. Some students have to get up early every morning on weekdays to get to school on time by bus or bike. It can be a long way from home to school. 查看答案
题型：问答题 简答题 金属材料的电阻率有以下特点：一般而言，纯金属的电阻率小，合金的电阻率大；金属的电阻率随温度的升高而增大，有的金属电阻率随温度变化而显著变化，有的合金的电阻率几乎不受温度的影响．根据以上的信息，判断下列的说法中正确的是（ ）A．连接电路用的导线一般用合金来制作B．电炉、电阻器的电阻丝一般用合金来制作C．电阻温度计一般用电阻率几乎不受温度影响的合金来制作D．标准电阻一般用电阻率随温度变化而显著变化的金属材料制作 查看答案