C
分析:首先,要看分?jǐn)?shù)是否是最簡分?jǐn)?shù),不是的,先把分?jǐn)?shù)化成最簡分?jǐn)?shù),再根據(jù)一個(gè)最簡分?jǐn)?shù),如果分母中除了2與5以外,不再含有其它的質(zhì)因數(shù),這個(gè)分?jǐn)?shù)就能化成有限小數(shù);如果分母中含有2與5以外的質(zhì)因數(shù),這個(gè)分?jǐn)?shù)就不能化成有限小數(shù);據(jù)此逐個(gè)分?jǐn)?shù)進(jìn)行分析再選擇.
解答:

化簡后是

,分母中只含有質(zhì)因數(shù)3,不能化成有限小數(shù);

是最簡分?jǐn)?shù),分母中含有質(zhì)因數(shù)2和5,能化成有限小數(shù);

是最簡分?jǐn)?shù),分母中含有質(zhì)因數(shù)2和5,能化成有限小數(shù);

是最簡分?jǐn)?shù),分母中含有質(zhì)因數(shù)2和5,能化成有限小數(shù);

是最簡分?jǐn)?shù),分母中含有質(zhì)因數(shù)3和5,不能化成有限小數(shù);
所以在分?jǐn)?shù)

中,能化為有限小數(shù)的分?jǐn)?shù)有3個(gè).
故選:C.
點(diǎn)評:此題主要考查什么樣的分?jǐn)?shù)可以化成有限小數(shù):必須是最簡分?jǐn)?shù),分母中只含有質(zhì)因數(shù)2或5.