The Elements of Verb Tenses

The word tense refers to the form a verb takes, which is based on two things, the time frame and the aspect.

Time Frame: whether a verb refers to the present, the past or the future.
Aspect: how the verb is related to that time. Here are the four kinds of aspect and their meanings:

Aspect	Meaning
Simple	at that time
Progressive	in progress during that time
Perfect	before that time
Perfect Progressive	in progress during and before that time

Combining time frame and aspect creates 12 possible combinations of forms, called tenses. The name of each tense tells which time frame and which aspect are being used: simple past tense, present perfect, future progressive, and so on. Identifying the correct frame is the first step in deciding which tense to use.

Present Time Frame is used when
a) talking about general relationships and events that occur frequently or regularly (present tense is often found in scientific and technical writing)
b) talking about anything related to the present moment (current events, letters and conversations, some informal jokes and stories).

Past Time Frame is used when talking about things which happened in the past and which are not connected to the present moment (most fiction and historical accounts, newspaper stories about events that occurred).

Future Time Frame is used when talking about something scheduled to happen or predicted to happen in the future.

The Twelve Verb Tenses

Present Time Frame

Form	Meaning	Use	Example
Simple Present	now	general relationships and timeless truths	It seems that time goes faster as we age.
		permanent states	Mary likes to travel abroad.
		actions that recur; habits	Tom works at the rec center every Saturday.
Present Progressive	already in progress now	actions in progress	Nia is studying for a test right now.
		repetition or duration	I am taking a math class this semester.
		temporary states and actions	Bob is living with his parents this summer.
		uncompleted actions	Bill and Val are still looking for an apartment.
Present Perfect	in the past but related to the present; time period is not finished	past events related to the present by time	My mom has visited Paris twice, so she won't join the trip to France.
		past events related to the present by logical relationship	Sandy has gotten very good at the computer, so she doesn't need this class.
Present Perfect Progressive	until and often including the present	repeated and/or continuous actions	Paul has been spending his weekends in the library since he moved into the dorm.
			I have been singing in a choir since I was in high school.

Past Time Frame

Form	Meaning	Use	Example
Simple Past	at a certain time in the past	states or general relationships that were true in the past	Tuberculosis was a common cause of death fifty years ago.
		habitual or recurrent actions that took place in the past	As a child I visited my grandparents every summer.
		specific events that took place in the past	They opened the store in 1982.
Past Progressive	in progress at a certain time in the past	interrupted actions	I was ironing when the phone rang.
		repeated actions and actions over time	She was taking classes for a few months.
Past Perfect	before a certain time in the past	actions or states that took place before other events in the past	They had gone out before the fire started.
Past Perfect Progressive	until a certain time in the past	continuous or repeated actions	When Henry and Linda met, they had both been studying French for two years.

Future Time Frame

Form	Meaning	Use	Example
Simple Present	scheduled or expected in the future	schedules	The boss is in Chicago on Thursday.
Present Progressive		definite future plans (sometimes w/ "going to")	I am going to finish my degree next year.
Simple Future	at a certain time in the future	predictions about the future	She will probably move soon.
Future Progressive	in progress at a certain time in the future	events happening at the same time as other future events	When we retire, the Smiths will already be living in Hawaii.
Future Perfect	before a certain time in the future	events happening before other future events	Janet will have gone out by the time we gather for the party.
Future Perfect Progressive	up until a certain time in the future	repeated and/or continuous actions	By New Year's, we will have been working on the project for seven months.