The only thing that James has to do is to enter the room and Mark immediately becomes angry.QUOTE]
1) How do you know that Mark immediately becomes angry?
2) James has only to come into a room to make Mark angry.
This means, as I said, that the only thing James has to do to make Mark angry, is come into the room. He doesn't have to speak, or breathe, or start an argument. It is merely the act of entering the room that angers Mark. James does not want to make Mark angry, nor is that his reason for entering. "Has only to" = "the only thing he needs to do is"
So for this purpose, we use the present simple (have/has) + only + full infinitive"
** James has only come into a room to make Mark angry.
This means that the only reason James has come into the room is specifically to make Mark angry. That was his purpose in entering the room. "Has only come" = "the only reason he has come"
For this purpose we use the present perfect (has come), separated by the word only.
** ( any difference between ' has only to ' and ' has only '?
Give me more examples. Thanks.
I have only to look at a chocolate biscuit, and I gain 2 kilos. (Sarcastic!)
He has only to dream about winning the lottery, and he wins. (I wish this were true!)
Dogs have only to smell a cat, and they immediately run after it!
I have only come into work to collect my pay.
They have only gone to the football game because they think the players are sexy.
He has only done the washing-up because I told him to.
