题目

有几个英语句子没看懂,麻烦解释下
1.It is more difficult to write simply,directly,and effectively than to employ flowery but vague expressions thay only obscure one's meaning.
从than后面开始句式就不懂了,vague和obscure不重复吗?
2.The knee is the joints where the thigh bone meets the large bone of the lower leg.
joint为什么用复数?
3.Acids are chemical compounds that,in water solution,have a sharp taste ,a corrosive action on metals,and the ability to turn certain blue vegetable dyes red.
为什么用a sharp taste,a corrosive action,the ability?(冠词不懂）

提问时间：2021-03-25

答案

1.than的句子里,有时候可以把than看作一个特殊的关系代词,后面可以直接跟动词,所以这里obscure是动词（vague是形容词,虽然两个词意思一样）.比如,He asks for more money than is needed.
2.joint指关节,关节是连接两个东西的,所以我觉得这里用复数更恰当,估计是固定用法吧.
3.taste和actiion都是可数名词,当然要加冠词a,后面ablility我觉得用冠词a也未尝不可.