be + verb-ing

The continuous aspect is expressed with the auxiliaryA helping verb used with main verbs to express mood, voice and tense. E.g.: I can't stand when I am disturbed. ("can", "am") be and the (present participle) -ing form of the verb. Depending on the timeA concept which is related to our perception of reality; that part of existence which is measured in seconds, minutes, hours, days, weeks, etc. of the actionA general term expressing that somebody or something does something, we use the past (was, were), present (am, are, is) or modal + infinitive (e.g. will be) form of be.

The continuous aspect focuses on the durationA concept, related to the continuous aspect, expressing that an action is in progress. E.g.: What are you doing? of an eventA general term expressing that somebody or something does something or that something happens. E.g.: An apple fell on Isaac’s head.. It expresses that the action was, is or will be in progressAn action is in progress when it is happening. E.g.: When I arrived he was surfing. ("he was surfing") at a particular point of timeA particular moment in time. E.g.: She came home at six. ("six") I was born in 1980. ("1980") or over a period of timeThe length of time between two points of time.. The point of time may be defined by a time expressionA word or group of words used in a particular situation. E.g.: Good morning, at six, on the sofa (now, at 5 o'clock yesterday, this time tomorrow) or a clauseA group of related words containing a subject and a verb. (when I came home, when I come home). For the period of time we can also use a time expression (all day yesterday) or a clause (while she was reading).

Examples of the continuous aspect:

Are you enjoying yourself? (now)
At 5 o'clock I was sitting on the bus.
When I came home she was sleeping.
She must be waiting for me. (now)
Johnny was playing computer games all day yesterday.
While she was reading, George was doing the dishes.
In January, I'll be living at my brother's.

Diagrams

Aspects
Aspects The perfect aspect