“Will you join us tonight?” “

“Will you join us tonight?”
“Oh ,I （）,but I have an essay to write.”

would love to

would love

would love to join

would love joining

“今晚你愿意和我们一起去吗？“
“噢，我很想去，但是我有一篇论文要写。”

would love to有本来打算去做某事，而由于某种原因没有做的意思。介词to不可以省略，后面的动作可以省略。