Present Prfect Continuous Tense
Present Perfect Continuous Tense: Present Perfect Continuous Tense is used to express the action that has been going for a period of time.
I have been doing the work since morning.
***Structure-1: Sub+have/has been+v+ing+ob+extension.
Have and has are used according to the rules of present perfect tense.
for is used if it is period of time, since is used for if it seems particular time.
They have been trying to do the work for two hours.
I have been waiting for you since morning.
She has been trying to memorize the poem for one hour.
They are playing football since morning.
I have doing the sums for two hours.
***Structure-2-: Sub+have/has+not+ been+v+ing+ob+extension.
They have not been starving for two days
It has not been raining since morning.