综合填空。根据短文内容及首字母提示在空白处填上适当的单词，使短文意思完整。
Airplanes are the newest kind of transportation. From early times, people tried to f 1 through the sky like
birds. About 100 years a 2 , someone took the first ride on an airplane. This ride lasted for less than one m 3 .
These first planes were very s 4 , too. Only one o 5 two people could fly in them at one time.
Today these p 6 are very big and fast. H 7 of people can travel in them at one time. W 8 them, people
can get f 9 one side of the United States to the other in less than one day. Traveling is very d 10 from the
way it was 100 years ago.
1.________ 2.________ 3.________ 4.________ 5.________
6.________ 7.________ 8.________ 9.________ 10.________
，
，则f(x)在点x=0处