PRESENT PERFECT TENSE

   Present Perfect Tense emphasizes that its PERFECT. Perfect it means "perfect". Not perfect as it is pretty, but the perfect means "complete, already, has just finished," and so forth. So, if you emphasize the "IS" it's then use the Present Perfect Tense is. The most striking examples of such: She has just gone.
   The formula of Present Perfect Tense is:
- positive     : S + have/has + V3
- negative    : S + have/has Not + V3

- introgative : Have/has + S + V3

after the Subject (S) then use "have" or "has" suitable partner. Have in this context means: already, been, just now. What is strange in English ES + Have not haves but HAS. So like this:

• He, She, It, John, Merry, Mufli : Has
• You, We, They, Ellen and Budi: Have

Examples of Present Perfect Tense

Positive    : She has gone (He just left)

Negatives : She has not gone

Introgative: Has She gone?

Remember, She has not go, nor She has going, nor has She goes. "Go" is the third form of the verb is "gone". Sequence changes in verb forms to Go is:

Go-went-gone.

  Another example:
-I have written english lesson for 30 minutes
-You have read my lesson since 2 PM

Note the verb changes:
Write - wrote - written (changed)
Read - read - read

I repeat
-I have written english lesson for 30 minutes.

Meaning:
I've written English language lessons for 30 minutes.

In the sentence above, emphasized "have" and now it's done, is no longer writing. But if your emphasis on "past 30 hours" then you use the Past Tense is more suitable.

Take another example, the positive:
-I have cleaned the floor
-He has drunk milk
-You have just broken the glass

  Introgative in Present Perfect Tense only appropriate formula above was reversed. Remember do not forget his partner to "Have" and "Has".

-Has She drunk milk?