现在完成时标志词

already

用在肯定句中（be动词、助动词、情态动词之后，实意动词之前）常与yet进行转换。例如：I have already finished the work.我已经完成这项工作了。改为否定句：I haven't finished the work yet.我还没有完成这项工作。改为一般疑问句：Have you finished the work yet?

before

表示之前发生的事情，放在句末

例如：I have been to this place before.我之前去过了这个地方

just

表示刚刚做过的事情，放在have/has后面

例句：I have just cleaned my room.我刚刚清理了我的房间