老师好，they代词的单复数形式上可能不是对应的:
https://www.moving.com/tips/what-you-need-to-know-when-moving-to-london/
这个网站的句子：You’re going to need to set aside about three months to acquire a U.K. workvisa, but there’s never a guarantee that you’ll succeed in getting oneand they’re not cheap to apply for.
they前面没形式上是复数的名词，不过语义上倒讲得通，如此是适合的吗？
这种指代是语境照应。听话人依据上下文语境，了解你此时的they指的是UK visas.
they指代前面提及的复数名词，是后照应指代。
