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
By the way, what are you going to do on Christmas?
顺便问一下，圣诞节你打算做什么？
This alone made our nine-day trip worthwhile.
光这件事我们9天的旅行就非常值得。
This is by far the largest cake in the world.
这是目前世界上最大的蛋糕了。