I have been (looking for) my lost keys,but I haven't found them till now括号中为什么要用

问题描述:

I have been (looking for) my lost keys,but I haven't found them till now括号中为什么要用
looking for

这句话整体是现在完成进行时,就是一直在做某件事.
句子翻译:我一直在找我丢失的钥匙,但是我现在还没找到.
look for意思是寻找.