[Q]: How does the sentence end?

Betty had perfectly white teeth while Erin had yellowed teeth; 

[A]: Betty offered her some whitening toothpaste.


[Q]: How does the sentence end?

Felicia loved going to the lake with friends but Samantha was not fond of it, since 

[A]: Samantha was a huge introvert.


[Q]: How does the sentence end?

The dog wagged it's tail at Monica but not at Jennifer, because 

[A]:
Monica had played with it before.