When workers are organized in trade unions, employers find it hard to lay them ________.
本题考查词组辨析。lay off意为“解雇”；lay aside意为“搁置”；lay out 意为“安排，布置”：lay down意为“放下；拟定”。
【参考译文】当工人们都由工会组织在一起，雇主将很难解雇他们。