"Before" is a preposition and an adverb, it doesn't have tenses.
No, present tense means you are currently doing something. To represent something you did before you would use the past tense.
The present perfect tense is: Have you ever seen the Taj before?
The present perfect tense of "see" is "have seen." It is formed by using the present tense of "have" or "has" with the past participle of "see." For example, "I have seen that movie before."
The verb is is the present tense.
Did is the past tense of do. Have done is present perfect.
The past tense of did is did. The present tense of did is do. The future tense of did is will do.
It was, (past tense) it is, (present tense) it will be( future tense)
Past tense I had Present tense I have Future Tense I will have
The present perfect tense of "watch" is "have watched" or "has watched." For example, "I have watched that movie before."
"Has" means something happened before the current time, ("is" is present) so it's past tense.
"Has" is in present tense. The past tense is "had".
No 'is' is present tense. am/is/are = present tense was/were = past tense