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Skin-diving （潛泳）is a new sport today．This sport takes you into a wonderful new world．It is like a visit to the moon! When you are under the water, it is easy for you to climb big rocks, because you are no longer heavy．

Here, under the water, everything is blue and green．During the day, there is enough light．When fish swim nearby, you can catch them with your hands．When you have tanks （罐）of air on your back, you can stay in deep water for a long time．But you must be careful when you dive in deep water．To catch fish is one of the most interesting parts of this sport．

Besides, there are more uses for skin-diving．You can clean ships without taking them out of the water．You can get many things from the deep water．Now you see the skin-diving is useful and interesting．

1．Skin-diving is going to take you to _______．

    A．the moon           B．be in danger     C．mountains              D．the deep water

2．You can climb big rocks under water because _______．

    A．you are stronger                                    B．the fish nearby help you

    C．you are lighter than on land             D．there is a lot of light

3．Under the water, a skin-diver _______ in the day time．

    A．can see everything clearly               B．can't see anything clearly

    C．can see nothing                             D．can see only fishes

4．With a tank of air on your back, you can _______．

   A．catch fish very easily                      B．stay under the water for a long time

   C．be in a safe place                            D．have more fun

5．From the passage we can know that skin-diving is _______．

   A．harmful                B．dangerous           C．useful and interesting      D．unuseful

Many scientists say that the world is getting hotter and hotter．If they are right , the ice at the North and South Pole will melt eventually．If this happens, the sea will  1  and may cover most  2  all of Singapore．This will force everybody to move to a  3  country．

       We know that the sun  4  the earth．The heat from the sun hits the  5  , and some of 6  goes back into the sky．However, factories and cars  7  a lot of carbon dioxide（二氧化碳）．When the gas rises into the sky, the heat from the sun can come  8  them but the heat from the ground cannot．It  9  near us in the sky and makes the  10  hotter and hotter every year．

Scientists call this the “greenhouse effect” because a greenhouse is a small glass  11  which is hot inside．It is used for  12  plants in cool countries．Many countries are  13  about the greenhouse effect．They are trying to stop factories and cars from sending  14  gases into the sky．Scientists are not sure when the world will get much hotter．Some people say that the greenhouse effect has  15  already and has begun to affect the world’s weather．

1．A．rise                          B．fall                         C．change                   D．disappear

2．A．a(chǎn)nd                          B．or                           C．but                         D．till

3．A．better                       B．larger                      C．safer                      D．farther

4．A．shines                   B．circles                    C．covers                    D．heats

5．A．ground                     B．sky                         C．mountain                D．forest

6．A．them                        B．it                            C．those                      D．such

7．A．make                        B．spread                    C．produce                  D．from

8．A．through                    B．over                       C．into                        D．toward

8．A．hides                        B．continues                C．follows                   D．stays

10．A．cloud                      B．a(chǎn)ir                          C．season                    D．temperature

11．A．building                   B．flat                         C．tool                        D．machine

12．A．putting                    B．storing                    C．cutting                    D．growing

13．A．excited                   B．disappointed            C．worried                  D．pleased

14．A．dangerous               B．harmful                   C．heavy                     D．useful

15．A．meant                     B．improved                C．started                    D．stopped