at present--at this time,now 此刻,现在
I am afraid I cannot help you at present.
for the present/moment-- temporarily,for now 暂时,目前
We're happy living i a flat for the present/moment but we may want to move to a house soon.
我认为后者会有暂时的含义,而前者没有,就这个区别吧.有时就是一些习惯用法.