96.1-40&97.8-29(关于some的用法的问题)

97.8
29.A mirage is an atomspheric optical illusion in what an observer sees a nonexistent body of water or an image of some object.

96.1
40.For thousands years,people have used some kind of refrigeration cooling beverage and preserve edibles.

这两题的错误都很明显
不过some后的名词为什么不用复数呢？
请指教？

没错，some有一种解释是＂某种＂后可以跟单数

ＪＪ可不可以把标题改一下，提问的具体格式置顶的帖子里有，主要是方便大家搜索，谢谢