I + Have + Past Participle of the verb.
For example: I have worked.
Both are correct depending on the situationdid not decide -- this is past simple negative and is used to talk about something in the past that is finished now.You did not decide what was right and you missed out.Have not decided -- this is present perfect negative and is used to talk about something that happened in the past that has a present result.You have not decided what is right and now you miss out.
not sure...anybody else???
Green seals are used on all Federal Reserve Notes dated 1928 to the present.
amphetamine use and abuse in the U.S. from the 1950s to the present.
Hudson
Actually, "have" is the present tense form for first and second person plural (I, you, we, they) while "has" is the present tense form for third person singular (he, she, it). For example: "I have, you have, we have, they have" versus "he has, she has, it has."
"Cannot" can't be used in the present perfect tense.
The present perfect tense is used when there is a connection with the past and the present. It is used to depict change, experience and a continuing situation. The future perfect tense, however, is used to talk about the past in the future.
The present tense or future tense can be used with "until".
Present perfect is formed with - have/has + past participle.The past participle proctor is proctored. So present perfect is have/has proctored.He has proctored us before.
The present perfect tense can be used to express experience, a change or a continuing situation.
The past participle is the verb that's used in the present perfect tense.
Sure, here's an example: "She has finished her homework before heading out to play soccer."
It is 'cost'. For example, if the noun used is first or third person plural, it is always 'have cost'; if the noun used is third person singular it is 'has cost'.Present perfect is have/has costThey/We/You/I have cost us a fortune.He/She/It has cost the school lot of money
Present Perfect Tense: I have; You have; he, she, it has; we have, you have, they have Past Perfect Tense: I had; you had; he, she, it had; we had; you had; they had Future Perfect Tense: I shall have; you will have; he, she, it will have; we shall have; you will have; they will have Note: has is used in the third person, singular present perfect tense.
The present perfect tense is used to express experience, change or a continuing situation.
The present perfect tense is used for an action that began in the past and that continues into the present. For example, "We have lived in the same house since 1997." is a sentence in the present perfect tense. "I have always liked chocolate." is the present perfect tense.