More than millions of years ago, there were deserts. Now about one fifth of the Earth's surface {#blank#}1{#/blank#} (be) deserts. The size of the world's deserts keeps {#blank#}2{#/blank#} (change). Deserts can be hot or cold. The Australian Desert is a hot desert, while the Gobi Desert is a cold desert. A desert is a very dry land and there is hardly any rain. The Sahara Desert in Africa receives less than 1.5 cm a year. {#blank#}3{#/blank#} it doesn't rain very often in deserts, sometimes even for years, there can be heavy rain suddenly. Because they are dry, deserts have wide changes in temperature each day. When the Sun goes up, it is very hot, even hot enough {#blank#}4{#/blank#} (fry) an egg on the ground. At night, the heat that {#blank#}5{#/blank#} (receive) by the ground during the day disappears {#blank#}6{#/blank#} (quick), and then it gets {#blank#}7{#/blank#} cold that water would turn into ice. Because {#blank#}8{#/blank#} the change, living in the desert is very difficult. Man can make deserts, but man can also stop {#blank#}9{#/blank#} (they) from getting larger and larger. Planting trees can prevent the sand from {#blank#}10{#/blank#} (spread).

    Last week Johnny {#blank#}1{#/blank#} (have) a very busy weekend. On Saturday morning, he cleaned his room. That {#blank#}2{#/blank#} (make) his mother very happy. In the afternoon, he did his math homework. It {#blank#}3{#/blank#} (be not) difficult. And in the evening, he {#blank#}4{#/blank#} (go) to visit his aunt with his parents in the countryside. They {#blank#}5{#/blank#} (eat) a big dinner and had a good sleep there. The next morning, he picked some strawberries and {#blank#}6{#/blank#} (take) them home. After lunch he played football on the school playground. That exercise makes him in good health. On Sunday evening, he watched TV for an hour at home and then {#blank#}7{#/blank#} (put) the books in his schoolbag for the next day.