欧洲地形以（    ）为主

根据短文理解，从A、B、C、D四个选项中选择最佳答案填空。

    I have a cousin. 1 name is Eric. He is 2. He likes music and he can play 3 very well. But he 4 want to join the music club. He wants 5 the art club. He wants to learn 6. I don't like music 7 art, I like sports. I can play tennis. I can 8 swim but I can't swim 9. I want to join the sports club. My friends are in that club. I want to play sports with 10.

有一台汽油发动机，汽缸工作容积指活塞从上止点到下止点所扫过的容积V，又称单缸排量，它取决于活塞的面积和活塞上下运动的距离（既冲程长）．如图为发动机在做功冲程中的示意图．设活塞的面积为S，冲程长为L，燃气对活塞的平均压强为p，请证明燃气对活塞的所做的功W=pV．

二次函数y=(x-1)²+2的最小值是  （     ）

某人在t=0时刻时，观察一个正在做匀加速直线运动的质点，现只测出该质点在第3s内及第7s内的位移，则下列说法正确的是（　　）