As the following Ngram graph shows, There was an important rise in frequency of The 2 "free of" phrases (blue and green strains) in the last one hundred years, and that raise appears to have come mostly on the expenditure of The 2 "free from" phrases" (pink and yellow lines):知乎，让每一次点击都充满意义 —— 欢迎来到知乎，发