WWW使用最普遍的是哪一种格式？（）
A．.HTML
B．.DOC
C．.TXT
D．DBF
参考答案：A
— Why do you often listen to the radio?
— To get some information _____.
[ ]
A. by air
B. on the air
C. in the air
D. from the air
再结晶退火
