[Q]: How does the sentence end?

Katrina cooked a chicken for Mary, since 

[A]: Mary did not how to cook a chicken very well.


[Q]: How does the sentence end?

Rachel didn't know how to be humble and Tanya did because 

[A]: Rachel got angry with people very easily.


[Q]: How does the sentence end?

Jen had to choose to buy either the camera or the goPro. She chose the 

[A]:
camera because she is always still.