Wrong. It was wrong for you to have gone.
Right. It was wrong for you to go.
Wrong. I ought to answer before that had happened.
Right. I ought to have answered before that had happened.
Revise. I intended to have told you.
336. Use an adverb of time to show that the subordinate clause differs in time from the main clause.
Wrong. The reason for the fertility of Iowa farm land is that an ice sheet spread over almost the entire area of the state.
Right. The reason for the fertility of Iowa farm land is that an ice sheet once spread over almost the entire area of the state.
Revise. One little corner of Iowa contains many steep hills because the ice did not reach it.