Tense allows for the sequencing of two or more noncontinuous events that occur in the same time period is perfect tense.
The perfect tense is a verb which indicates the actions which occurred earlier in the time and the resultant action is focused.
For example, the children have completed the homework.
The above sentence gives the information about the past action of 'doing homework' which is now completed, referring to the result of the action occurred earlier.
The speaker is very nervouse
