试题题干
Fill in the blanks with the appropriate words given in the group.
lone, alone, lonely, if, whether, so that
You’d better leave things 
you don’t know how to deal with them.
参考答案
试题解析
句意：如果你不知道如何处理这些事情，你最好别管闲事。leave ... alone 不管不顾···；if引导条件状语从句。