I stack you stack he stacks we stack you stack they stack
Present continuous
I am stacking you are stacking he is stacking we are stacking you are stacking they are stacking
Preterite
I stacked you stacked he stacked we stacked you stacked they stacked
Preterite continuous
I was stacking you were stacking he was stacking we were stacking you were stacking they were stacking
Present perfect
I have stacked you have stacked he has stacked we have stacked you have stacked they have stacked
Present perfect continuous
I have been stacking you have been stacking he has been stacking we have been stacking you have been stacking they have been stacking
Pluperfect
I had stacked you had stacked he had stacked we had stacked you had stacked they had stacked
Pluperfect continuous
I had been stacking you had been stacking he had been stacking we had been stacking you had been stacking they had been stacking
Future
I will stack you will stack he will stack we will stack you will stack they will stack
Future continuous
I will be stacking you will be stacking he will be stacking we will be stacking you will be stacking they will be stacking
Future perfect
I will have stacked you will have stacked he will have stacked we will have stacked you will have stacked they will have stacked
Future perfect continuous
I will have been stacking you will have been stacking he will have been stacking we will have been stacking you will have been stacking they will have been stacking
Conditional
Present
I would stack you would stack he would stack we would stack you would stack they would stack
Present continuous
I would be stacking you would be stacking he would be stacking we would be stacking you would be stacking they would be stacking
Past
I would have stacked you would have stacked he would have stacked we would have stacked you would have stacked they would have stacked
Past continuous
I would have been stacking you would have been stacking he would have been stacking we would have been stacking you would have been stacking they would have been stacking