know的名词是knowledge；
knowledgen.知识；学问；学识；知晓；知悉；了解
She has acquired a good knowledge of English.
她英语已经学得很好。
Our knowledge of the disease has advanced considerably over recent years.
近年来我们对这种疾病的了解深入多了。
To my certain knowledge he was somewhere else at the time.
我敢肯定他当时在别处。
