题目

Sam and Joe were astronauts. There was once a very dangerous trip and many experienced astronauts knew there was only a small chance of coming back alive. Sam and Joe, however, thought it would be exciting though a little dangerous. “We’re the best men for the job,” they said to the boss. “There may be problems, but we can find the answers.” “They’re the last people I’d trust,” thought the boss. “ But all the other astronauts have refused to go.”     Once they were in space, Joe had to go outside to make some repairs. When the repairs were dong, he tried to get下列物质的用途，主要利用物质的化学性质的是A.用铜做导线B.用铁制炊具C.用煤气做燃料D.用金刚石切割玻璃