QUES: unacceptable
ANS: Five pounds are a lot of money.

QUES: acceptable
ANS: Stephen persuaded Ben to be careful.

QUES: acceptable
ANS: Bill left when it is certain that no one else was awake.

QUES: unacceptable
ANS:
Sodium is a little too peppy for me to want to try mixing and water in a teacup.