题目

Maybe you are an ordinary student.38． This is not necessarily so.Anyone can become a better student if he or she wants to.Here’s how: Plan your time carefully.When planning your work,you should make a list of things that you have to do.After making this list,you should make a schedule of your time.First arrange your time for eating,sleeping,dressing,etc,then decide a good,regular time for studying.39． A weekly schedule may not solve all your problems,but it will force you realize what is happening to your time. Make good use of your time in class.40． Listening carefully in c下列各种制备方法中，前者是物理变化，后者是化学变化的是（　　）A．工业制氧气；实验室制氧气B．工业制氢气；实验室制氢气C．工业以CO2制干冰；实验室以水制冰D．工业开采金刚石；实验室以石墨制金刚石