[Q]: How does the sentence end?

Jessica was light headed and confused but not Elena because

[A]: Jessica had been exposed to harmful fumes.

[Q]: How does the sentence end?

Matthew was helping Leslie download a new security update on their computer for

[A]: Leslie forgot how.

[Q]: How does the sentence end?

Emily gave a donation to the shelter while Cynthia didn't, because

[A]:
Cynthia was very poor and in need.