Copula
n. 系词, 介体, 接合部\\n[医] 介体; (舌)联桁; 交配
✅ 同义词
📖 牛津释义
copula
n
(grammar) type of verb that connects a subject with its complement 系词（即连系动词, 用以连结主语及其补语）
In `George became ill', the verb `became' is a copula. 在Georgebecameill一句中, became是系词.
🗣️ 情景例句
Thanks a lot. Bye.
多谢，再见。
He must have been an outstanding student.
他一定是个优秀学生。
it must be known to any kind of radio astronomer in the universe.
这个频率是宇宙中任何射电天文学家都应该熟悉的。