In English, "a" and "an" are called the indefinitearticle, and "the" is called the definite article.
在英语中，“a”和“an”被称为不定冠词，“the”被称为定冠词。
2
Article 4. There are three different terms of validity of resident identity CARDS: 10 years, 20 years and an indefinite number of years.
第四条居民身份证的有效期限分为十年、二十年、长期三种。
3
Based on the quality of linear operation about indefinite integral, the article puts forward an indefinite integral principle of making linear combination and reducing power of integrand.