in earnest
Seriously; in a determined way. Often used like a predicate adjective. Sometimes used with dead, for emphasis.
The beaver was building his dam in earnest.
Bill did his homework in earnest.
Betty's friends thought she was joking when she said she wanted to be a doctor, but she was in dead earnest.
in effect
The same in meaning or result.
The teacher gave the same assignment, in effect, that she gave yesterday.
Helping your mother with the dishes is in effect earning your allowance.
Necessary to obey; being enforced.
The coach says that players must be in bed by midnight, and that rule is in effect tonight.
in error
Wrong; mistaken.
You were in error when you assumed that he would wait for us.
in evidence
Easily seen; noticeable.
The little boy's measles were very much in evidence.
The tulips were blooming; spring was in evidence.
in fact
in point of fact
Really truthfully. Often used for emphasis.
No one believed it but, in fact, Mary did get an A on her book report.
It was a very hot day; in fact, it was 100 degrees.
I didn’t say that. In fact I said quite the opposite.
in favor of
On the side of; in agreement with.
Everyone in the class voted in favor of the party.
Most girls are in favor of wearing lipstick.
in fear of
Fearful of; afraid of.
They live so close to the border that they are constantly in fear of an enemy attack.
in for
Unable to avoid; sure to get.
The naughty puppy was in for a spanking.
On Christmas morning we are in for some surprises.
We saw Father looking angrily out of the broken window, and we knew we were in for it.