地壳运动改变着地球表面的基本形态，褶皱构造可形成（     ）

如图所示，在“探究物体的动能大小与哪些因素有关”的实验中，小球由斜面某位置滚下，撞击水平面上的小木块．

通读下面短文，掌握其大意，然后在每小题所给的四个选项中，选出一个最佳答案。

    It's a fine Saturday morning. There are many people in the park. Many of 1  are young and some are old.

    Some children are 2  games over there. Two boys are playing  3 their toy bats. There is a lake in the park. The water is 4  .  There are some 5  on the lake.  6  the lake a young man is reading. There is a house near the lake. Beside 7 house two men are working. Look at that big tree! There are some birds 8  it. Under it are some men. Four of them are playing cards. One of them is looking at two cats. The cats are 9 up the tree. What do they 10  to do? They want to catch the birds.