能问出此问题，说明在学语法方面有探究精神，不可小觑。
此类词组应该有无数个，可根据所学到的单词量级自己任意按逻辑意义组合。
系动词后面加上形容词、名词、
介词短语以及方位副词，甚至是
不定式等等都可以组合为系表短语。先有语言，后有语法，所以对你所提问题的解释应该有许多仁智看法。
一个动词后跟名词做宾语，此动词可称为
实义动词中的
及物动词；若某动词后紧随的是形容词，且其后再无名词被此形容词修饰，则前者肯定是系动词。照此法可组出无数系表词组。
如：be careful, be quiet, be clever, be red, be in black, am a postman, is an answer to the question, is one of the best cooks, are students, are in their vocations, has been there, will be a doctor, must be a mouse, may be rainy, be up to sb., be on time, be about to do, be similar to, be able to do, come true, keep healthy, stay foolsh, get warm, become mad, grow better, fall ill, seem very sad, look happy, prove false, turn green, rest a question, smell sweet, feel soft......