The earth was just {#blank#}1{#/blank#} cloud of dust after the “Big Bang”. The earth exploded {#blank#}2{#/blank#}(loud) with fire and rock. They were in time to produce carbon, nitrogen, water vapour and other gases, which were {#blank#}3{#/blank#}(make) the earth's atmosphere. As the earth cooled down, water began to appear on its surface. It allowed the earth to dissolve {#blank#}4{#/blank#}(harm) gases. Then life began to develop.

    Small plants multiplied and filled the oceans and seas with oxygen. This encouraged the {#blank#}5{#/blank#}(develop) of early shellfish and fish. Land animals such as insects, reptiles and dinosaurs {#blank#}6{#/blank#}(appear) after green plants came into being. Small clever animals spread all {#blank#}7{#/blank#} the earth. They are putting too much carbon dioxide into the atmosphere, {#blank#}8{#/blank#} prevents heat from escaping from the earth into space. {#blank#}9{#/blank#} life will continue on the earth for millions of years to come will depend on whether this problem can {#blank#}10{#/blank#}(solve).

    Friends play an important part in our {#blank#}1{#/blank#} (life). Though we may take friendship for granted, we often don't clearly understand {#blank#}2{#/blank#} we make friends. While we get on {#blank#}3{#/blank#}(good) with many people, we are usually friends with only a few—for example, per student usually {#blank#}4{#/blank#} (have) about 6 friends. In all the cases of friendly relationships, two people like one another and enjoy {#blank#}5{#/blank#} (be) together. {#blank#}6{#/blank#}fact, as we get to know people, we take into account things like age, race, economic condition, social position, and intelligence. Although these things are not of great {#blank#}7{#/blank#} (important), {#blank#}8{#/blank#} is more difficult to get on with people when there is an obvious difference in age and background. Compared with marriage, there are no friendship ceremonies to {#blank#}9{#/blank#} (strong) the connection between two people. But the mutual（彼此的）understanding that results from common experiences and emotions does seem to create a powerful bond, {#blank#}10{#/blank#} can overcome difference in background, and break down barriers（障碍）of age, class and race.

    A neighborhood watch is an {#blank#}1{#/blank#} (organize) group of people who have volunteered to help prevent crime in their neighbourhood. They do this by {#blank#}2{#/blank#} (keep) an eye on their neighbors' households, patrolling the streets and contacting the police when they see wrong {#blank#}3{#/blank#} (activity). Neighbourhood watches have {#blank#}4{#/blank#} of history, but they{#blank#}5{#/blank#} (introduce) to modem American cities after the public was shocked {#blank#}6{#/blank#}( hear) how a woman was murdered in New York city while a number of witnesses stood by and did nothing. {#blank#}7{#/blank#}(recent), however, some people have strongly objected to the organization after n neighborhood watchman shot to death a black teenager, {#blank#}8{#/blank#} was on his way home in the evening. The shooting has led to a new suggestion {#blank#}9{#/blank#} neighborhood watchmen shouldn't carry guns while on patrol. Many neighborhood watch committees disagree {#blank#}10{#/blank#} this idea, saying that it will discourage volunteers from patrolling more dangerous districts. Besides, since Florida state law allows the carrying of guns, such advice is useless.