A practical english grammar - Vyssaja skola 1978

Noun clauses in indirect speech
Sound symbols

It is often necessary to represent an idea, question, or statement as having been thought of, asked, or pronounced by someone else. We do this in the form of indirect speech, and the original utterance, usually somewhat changed, is presented in the form of a noun clause:

Original utterance: “I am glad to be here.”

A report of this utterance: He says (that) he is glad to be here. The connecting word that in clauses of this type may be omitted, and usually is, in informal English.

As a rule, the tense of reported speech is affected by the tense of the main verb in the sentence. Using the same original utterance as above, but putting the report of it in the past tense, we have this form.

He said (that) he was glad to be here.

The speaker has choice in the tense of the verb in the clause. If he wants to stress that the action of the main verb and that of the verb in the clause are contemporary, he makes them agree. Or he may use the present tense in the clause to suggest that the information contained there is still true or is still of interest.

The settlers learned that the land in the valley was fertile. (Present condition of the land in the valley is of no interest at the moment.)

The settlers learned that the turkey is an elusive bird. (It was and still is elusive.)