得癌症死的明星:a/an与one哪个比较正式

a/an与one哪个比较正式 有些糊涂one和a，an 之间 half an hour 与a half hour a /an 是不是实词 What do you think of the story? Oh,it is really ? exciting one. A.a B.an C.the D./ He has just bought an Australian car.He bought one a short time age. Intel Pentium4 506与P4 2.4A哪个比较好？ 元和块,哪个比较正式 CHN与PRC,哪个缩写更正式?! A man wanted to buy an ass .He went to the market,and saw a likely one.是什么意思？