just

adverb [时间副词]正好，恰好；正当…时；不少于，同样；差一点就不，勉强；刚才，刚刚；正在，正要；只是，仅仅是；确实，完全；请，就；可能，也许；表示赞同

If you say that you are just doing something, you mean that you are doing it now and will finish it very soon. If you say that you are just about to do something. ^{正在; 正要}