Has Understand or Understood?
Both Understand and Understood Are Grammatically Correct. the One That You Have to Use Depends on What You Want to Say. Understand Is the Present Tense Verb...
Both understand and understood are grammatically correct. The one that you have to use depends on what you want to say. Understand is the present tense verb. If you are talking about something that you learn or know now, you can use understand.
Is it correct to say I have understood?
As Aardvark says, I did understand is (simple) past tense; I have understood is present perfect. In the most general terms, the simple past says something about the past; the present perfect says something about the past and something about the present.
When use understood and understand?
Understood is in past tense whilst understand is present tense. Understood: "After I made her cry, I finally understood why making fun of others was wrong." Understand: “I understand now that words can hurt others."