请教英语高手两个小问题，急！！！！！先谢谢您啦 高中英语

1..请看以下两个句子：
He took out a piece of paper ,on which 【were】 written some words.
There is a library ,in front of which【 stand 】 two stone lions. 以上两句中加了【】的单词都没用第三人称单数，但前面却是paper 和 library，是不是语法要求？请详细解释下，谢谢^_^
2..By serving others ,a person focuses on someone other than himself or herself,【】can be very eye-opening and rewarding. 请问此处的【】中为何要填which而不是who？ 请说明。

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