Present perfect, past perfect or future perfect.

This month, we have learned about the great sphinx.

http://www.englishpage.com/verbpage/presentperfect.html

Thank you.

You're welcome.

past perfect!

In this sentence, the verb tense being used is the present perfect tense. The present perfect tense is formed by using the auxiliary verb "have" (or "has" for third-person singular) followed by the past participle of the main verb.

To identify the tense of a sentence, you can follow these steps:
1. Look for auxiliary verbs like "have," "has," "had," "will," "shall," "would," "should," "could," "may," "might," "must," etc.
2. Check if the auxiliary verb is followed by the past participle of the main verb.

In the given sentence, we can see that "have" is used as the auxiliary verb, and "learned" is the past participle of "learn". Therefore, the present perfect tense is being used.