英语新视野完型填空 Directions:There are 10 blanks in the following pa

英语新视野完型填空
Directions:There are 10 blanks in the following passage.For each blank there are four choices marked A,B,C and D.You should choose the ONE answer that best completes the passage.Ten mark the corresponding letter on the Answer Sheet with a single line through the center.
I often hear some old people say that when they were young,the rivers and lakes were very clean.They swam in them and even drank the water directly from them.There _(46)_ be lots offish and other living things in the rivers.But now _(47)_ the pollution,there aren't many fish left.In some of the rivers there are no fish at all.The water has been polluted and no longer _(48)_ for swimming or drinking,as a lot of _(49)_ are present in the water.In some places it is not safe to eat the fish.Water pollution is mainly caused by _(50)_ from factories and cities.They throw all the waste into the river _(51)_ cleaning them.Gases from factories and cars go up into the _(52)_ and the wind carries them far away.Later they come down with the rain.That is acid rain (ESN).Fish eggs and young fish are _(53)_ by even a little acid rain in the water.Acid rain is becoming a big _(54)_ all over the world today.Canada and some countries in northern Europe have the problem.In Canada for example,a lot of trees are _(55)_ because of acid rain.
46.A.used B.used to C.will D.to
47.A.because B.causing by C.because of D.caused by
48.A.safe B.safety C.dangerous D.danger
49 A.persons B.animals C.fish D.germs
50.A.people B.waste C.paper D.products
51.A.by B.after C.without D.for
52 A.water B.rivers C.heaven D.air
53.A.produced B.killed C.died D.saved
54.A.problem B.question C.success D.difficult
55.A.died B.death C.die D.dying

46=b used to be
47=c because of
48=a safe for
49=d germs细菌
50=b 这里乍一看我选的是WASTE,水污染是由工厂和城市的垃圾造成的.
不过应该是 THE WASTE,因为后面有from factories and cities.用THE 特指从工厂和城市来的垃圾.
但是看下面一句,THEY THROW.这里的THEY是指前面一句空格里面的谓语.
所以应该是人,最后选了PEOPLE.
51=c
52=d
53=b killed by
54=a
55=a died 前面有for exsample这里是举例,
说的是已经发生过的事,所以是过去时.
希望我解释的够清楚