一…一…yī…yī…
1.分别用在两个同类的名词前面。{[used before two nouns of the same kind]}
a)表示整个{[indicating the whole] all; the whole}:～心～意{wholeheartedly}|～生～世(人的一生)。{one's whole life; all one's life}
b)表示数量极少{[indicating a very small amount] each; every; single}:～针～线{a single needle or piece of thread}|～草～木{every grass and tree}|～言～行。{every word and deed}
2.分别用在不同类的名词前面。{[used before two nouns of different kinds]}
a)用相对的名词表明前后事物的对比{[use two relative nouns to indicate contrast]}:～薰～莸(比喻好的和坏的有区别)。{a fragrant herb and a blade of stinking grass;(fig.) there is difference between the good and the bad}
b)用相关的名词表示事物的关系{[use two related nouns to indicate their relationship]}:～本～利(指本钱和利息相等)。{capital and profit; profit proportionate to the capital}
3.分别用在同类动词的前面,表示动作是连续的{[used before two verbs of similar meaning to indicate two successive actions]}:～瘸～拐{limping along}|～歪～扭。{twist and crook}
4.分别用在相对的动词前面,表示两方面的行动协调配合或两种动作交替进行{[used before two relative verbs to indicate the coordination or alternation of the two actions]}:～问～答{one asking and the other answering}|～唱～和{one singing and the other echoing; sing the same tune; collude with each other}|～起～落{rise and fall in turn; up and down}|～张～弛。{alternate tension with relaxation}
5.分别用在相反的方位词、形容词等的前面,表示相反的方位或情况{[used before two opposite nouns of direction or two opposite adjectives to indicate opposite directions or situations]}:～上～下{one above, one below}|～东～西{one east, one west; poles apart}|～长～短。{one long, one short}