问题 填空题
选词填空。
    
that foot  the  fall  do  try  they  slow  both  of
     Galileo lived in the city of Pisa, where there is a leaning tower about 180 __1__ high.  From the top
 __2__ the tower Galileo dropped a light ball and a heavy ball exactly at __3__ same time.  They __4__ 
 fell at about the same speed and hit ground together.  He __5__ it again and again.  Every time he got the
  same result.  At last, he decided __6__ he had found the truth about __7__ objects.  As we know now,
  heavy objects and light objects fall at the same speed unless air holds __8__ back.  A feather falls
__9__ than a stone only because the air holds the feather back more than it __10__  the stone.
答案

 1. feet   2.  of        3.  the       4.  both              5.  tried

6.  that  7.  falling   8.  them    9.  more slowly   10.  does

单项选择题
单项选择题