45．A．hear      B．think    C．look        D．tell

(A)

The World’s Water Shortage(缺乏)

    The world is not only hungry，but it is also thirsty for water．This may seem strange to you，  since nearly 70 percent of the earth’s surface is covered with water．But about 97 percent of this  huge amount is sea water，or salt water．Man can only drink and use the other 3 percent--the flesh water from rivers，lakes，underground，and other sources．And we cannot even use all of that．because some of it is in the form of icebergs(冰山)and glaciers(冰河)．Even worse，some of it has been polluted．

    However，as things stand today，this small amount of fresh water is still enough for us．But  our need for water is increasing rapidly--almost day by day．Only if we take steps to deal with  this problem now can we avoid a serious worldwide water shortage later on．

    We all have to learn how to stop wasting our valuable water．One of the first steps is to develop ways of reusing it．

    Today in most large cities．water is used only once and then sent out into a sewer(下水道)  system．From there it returns to the sea or runs into underground storage tanks．But it is possible  to pipe used water to a purifying plant(净化工厂)．There it can be treated with chemicals so that  it can be used again，just as if it were fresh from a spring．

    But even if every large city purified and reused its water，we still would not have enough．All    we’d have to do to make use of the vast reserves of sea water in the world is to remove(去除)the    salt．

    If we take these steps we’ll be in no danger of drying up．

    44．A．taller    B．stronger         C．older       D．better