A：轮船的螺旋桨旋转时,向后推水,水同时给螺旋桨一个反作用力,推动轮船前进
B：发射火箭时,燃料点燃后喷出的气体给空气一个作用力,推动火箭前进
C：马拉车前进,只有马对车的拉力大于车对马的拉力时,车才能前进
D：一个作用力和它的反作用力的合力为零
亚里士多德曾经说过：“两个铁球，一个10磅重，一个l磅重，同时从高处落下来，10磅重的一定先着地，速度是l磅重的10倍。”这句话使伽利略产生了疑问。他想：如果这句话是正确的，那么把这两个铁球拴在一起，落得慢的就会拖住落得快的，落下的速度应当比l0磅重的铁球慢；但是，如果把拴在一起的两个铁球看作一个整体，就有11磅重，落下的速度应当比10磅重的铁球快。这样，从一个事实中却可以得出两个相反的结论，这怎么解释呢？
用方框内所给的单词，根据句意用其适当形式填空
comfort buy your be rain least build go fortieth miss
⑴Tomorrow will be my father’s ____ birthday.
⑵Don't go out. It ____ outside now.⑶This sofa is very ____ to sit on.⑷Today is hot. Why not ____ swimming!----That's a good idea.⑸Millie and Simon live in the same____ .⑹Helen often ____ the early bus. So he is often late for school⑺My answers are different from ____ ⑻Outside the garden there ____ a bus stop and many tall buildings.⑼At ____ thirty students go to school by bus in my class.⑽You can ____ a lot of souvenirs here.
