singular-plural alternation. Having said that, I do think it is actually the same kind of phenomenon. Semantics is stepping in and influencing the verb agreement — it is not always a purely syntactical selection.知乎，让每一次点击都充满意义 —— 欢迎来到知乎，发现问题背后的世界。请您尽快回复并提供帮助�