Ambassador Power said governments needed to stop spreading fear, in part by unnecessarily putting restrictions on returning volunteers who had been to the infected countries.
by前是否省略了caused等动词？
网友回答
The hours dragged by as I waited for Dad to finish work. 请解释一下...答：drap by是固定用法，“经过”。by有“过”的意思，类似的：walk by、pass by as 在这里有点类似when，但喜欢纠结语法的老师会说when语气更强，但语感这东西难以言传....
网友回答
by prep
4. followed by a gerund to indicate a means used: he frightened her by hiding behind the door.
By putting restrictions on returning volunteers, governments are spreading fear. 哪不好懂啊？