從句子意思上看,這道題的最佳答案應該是 someone。
就這個句子而言,空格處可以填 someone,也可以填 anyone,但不宜填 everyone或no one。
這不是一個語法問題,而是一個語境的問題——因為,只要語義需要, everyone 后接定語從句是完全可能的。如:
Everyone who knew him liked him. 認得他的人都喜歡他。
Everyone who helped gets a share in the profits. 凡是幫過忙的就得到一份利潤。
We kept seats for everyone who had paid. 我們給已經付了款的人都留了座位。
He looked suspiciously at everyone who got off the plane. 他用懷疑的目光打量著每一個從飛機上走下來的人。