Present Perfect Continuous

Present Perfect Continuous
The Present Perfect Continuous is used to talk about an action that started in the past and continued to the present, stating an ongoing action that has started at a point in the past.
It is formed by the present perfect of the verb “to be” (have/has) + been + the base of the main verb + (ing)
It is frequently used with a time reference to show when the action started in the past or for how long it has continued. If the exact starting time of action is known, use ‘since’. If the amount of time is known use ‘for’.
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In the negative form use present perfect of the verb “to be” (have/has) + not been + the base of the main verb + (-ing)
In the interrogative form, use the subject + the present perfect of the verb “to be” (have/has) + been + the base of the main verb + (-ing)