four sentences..

1. If you confuse everybody, they are misdirected, puzzled. If you confound everybody, they are abashed, put to shame, rendered speechless. (In either case, that's a pretty potent look, to have such an effect!)

2. Someone could be standing by the door by pure chance. If you say he was standing at the door you imply that he is there for some reason connected with the door - e.g. he is waiting for someone to come out, or to be asked to go in.

3. Prudent means careful, cautious, but doesn't necessarily imply knowledge or wisdom. Sagacious means wise, in a slightly ponderous way. Sapient also means wise, but is such an old-fashioned and pompous word that it is rarely used seriously - it is often ironic or jocular.

4. Exasperation and ire vary in intensity; they can be of any degree from quite mild irritation, and if you used them to describe serious anger you might need an intensifier. (Ire is rather old-fashioned, though.) But fury is always serious; it implies an impending or actual loss of control. A furious person is dangerous. Outrage is the odd one out here because it implies more than anger; if you are outraged your moral sense has been offended. (You could feel exasperation, ire and even fury if your two-year-old smeared shoe polish around a newly-painted room; you would not feel outraged.)

Thanks syntinen.That was a good explanation.