one和that都可以用作替换词.例如: A happy person is said to have a sunny disposition and a happy life to be one filled with sunshine. Animal social systems range from the temporary coupling of earthworms to the complex structures of ant societies, in which group interests so overshadow individuality that the relationship of individual to group is like that between cell and organism. 不过,在上面两个句子中,one和that却不能够互相交换使用.这是因为:one一般用来代表有不定冠词的名词,比如,第一句中的one等于a happy life;而that一般用来代表有定冠词的名词,如第二句中的that就替换了the relationship. 尽管我们不能把one和that互相交换使用,但是有时也可见到,the one取代that如: They(指the needles)weresometimes on my hands and arms, Both one and that can be used as replacement words. For example: A happy person is said to have a sunny disposition and a happy life to be one filled with sunshine. Animal social systems range from the temporary coupling of earthworms to the complex structures of ant societies However, in the above two sentences, one and that cannot be used interchangeably. This is because: one is generally used to: Represents a noun with an indefinite article. For example, one in the first sentence is equal to a happy life; and that is generally used to represent a noun with a definite article, as in the second sentence that replaces the relationship. Although we cannot Use one and that, but sometimes it can be seen that the one replaces that: They(refer to the needles) were sometimes on my hands and arms,