Verb tenses relate directly to the time in which an action takes place. Past tense verbs focus on actions that already occurred or began at some point in the past. Present tense verbs focus on action that is currently occurring or beginning currently. Future tense verbs focus on actions that will occur at some point in the future or will begin at some point in the future.
Simple past verbs refer to events that took place in the past and are generally denoted by the "--ed" suffix, such as in the word "finished." Simple present verbs refer to events that are regular or permanent but do not require additional words or letters, such as the word "finish". Simple future verbs refer to action that has not begun yet but will at some point in the future and are denoted by the addition of the word "will" in front, such as the verb "will finish." Irregular verbs do not use the standard "-ed" or "will" to denote past and future tense, such as the word "run" that has "ran" for the past tense.
Past perfect verb tense refers to events that occurred prior to another event and are denoted by the addition of the word "had," such as the phrase "had finished" in the phrase "I had finished my homework before going outside." Present perfect verb tense refers to events that were recently completed and denoted by the words "has" or "have," such as in the phrase, "I have finished my homework." Future perfect tense refers to events that will occur prior to another action and are denoted by the use of the words "will have" or "shall have," such as in the phrase, "I will have finished my homework by the time I go outside."
Continuous verbs use the present participle of the verb, along with the inclusion of a version of the verb " to be" to denote an action that is still occurring. The present participle is the verb with an appropriate "-ing" conclusion. For instance, the sentence, "I have been working on my homework all day," uses the "been" form of "to be" and the present participle "working." By using the word "have," the verb becomes a present perfect progressive. The suggestion by the sentence is that the subject has worked on her homework for a considerable amount of time and is still working on it at present.