航天航空控制系统应用:how fast does an aeroplane travel??

how fast does an aeroplane travel?? how fast does a balloon travel? How about an overplance?How about a space shuttle? how fast does a balloon travel? How fast does a balloon travel? how many teeth does an adult have? How long does an elephant live? Does TV have an impact on the audience? How? -----does the new plane fly in a minute?横线中填A.how longB.how fast为什么这么选 how does computer works??? how does it feel?