问题
选择题
目前人类还难以利用的水资源是（ ）
A．河水
B．湖泊淡水
C．浅层地下水
D．冰川融水
答案
地球的淡水资源仅占其总水量的2.5%，而在这极少的淡水资源中，又有70%以上被冻结在南极和北极的冰盖中，加上难以利用的高山冰川和永冻积雪，有87%的淡水资源难以利用．人类真正能够利用的淡水资源是江河湖泊和地下水中的一部分．
故选：D．
搜题请搜索小程序“爱下问搜题”
目前人类还难以利用的水资源是（ ）
A．河水
B．湖泊淡水
C．浅层地下水
D．冰川融水
地球的淡水资源仅占其总水量的2.5%，而在这极少的淡水资源中，又有70%以上被冻结在南极和北极的冰盖中，加上难以利用的高山冰川和永冻积雪，有87%的淡水资源难以利用．人类真正能够利用的淡水资源是江河湖泊和地下水中的一部分．
故选：D．
When I entered Berkeley，I hoped to earn a scholarship.Having been a StraightA student，I believed I could ____tough subjects and really learn something.One such course was World Literature given by Professor Jayne.I was extremely interested in the ideas he ____in class. When I took the first exam，I was ____ to find a 77，Cplus，on my test paper，____ English was my best subject.I went to Professor Jayne, who listened to my arguments but remained ____. I decided to try harder.Although I didn't know what that ____because school had always been easy for me.I read the books more carefully，but got another 77.Again，I ____with Professor Jayne.Again，he listened patiently but wouldn't change his ___. One more test before the final exam.One more ____ to improve my grade.So I redoubled my efforts and，for the first time, ____the meaning of the word “thorough”．But my ___ did no good and everything ___ as before The 1ast hurdle(障碍)was the final.No matter what ____ I got，it wouldn't cancel three Cpluses.I might as well kiss the ____ goodbye. I stopped working hard.I felt I knew the course material as well as I ever would.The night before the final，I even ____ myself to a movie.The next day I decided for once I'd have ____ with a test. A week later，I was surprised to find I got an A．I hurried into Professor Jayne's office.He ______to be expecting me.“If I gave you the As you ____，you wouldn't continue to work as hard.” I stared at him，____ that his analysis and strategy(策略)were correct.I had worked my head ____，as I had never done before. I was speechless when my course grade arrived：Aplus.It was the only Aplus given.The next year I received my scholarship.I've always remembered Professor Jayne's lesson：you alone must set your own standard of excellence.
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