A man may usually be known by the books he reads as well as by the companies he keeps, for there is a companionship of books as well as of men.
书上的句子。
1）是不是应该by the company he keeps, 复数用错误？
2) 请教老师company, companion, companionship 这3个单词作伴随之类意思时，到底有什么不同？
1 company表示“伴随”意义时，为不可数名词，所以用复数为错误，应删去S。
2 companion为可数名词，意为：朋友、伙伴、同伴。companionship, 可数名词加词尾 - ship, 将可数名词变为抽象名词，表示关系。比如，friendship, partnership, companionship, relationship 具体你可查词典。