____ Helen’s knowledge and vocabulary expanded, she asked more and more questions.
A．When B．While C．As D．Before
I didn’t know I was spelling a word or even ____ words existed.
A．that B．what C．which D．one
In a way, Pompeii is like a time capsule ____ a frozen moment in history.
A．protecting B．preserving C．preventing D．protesting
By the time some scientists ____ the lost towns, they ____ an awesome historical site.
A．had found, had found B．found, found
C．found, had found D．had found, found
He constantly gets into awkward and absurd situations, ____ audience can be greatly amused.
A．which B．where C．that D．what
When this happens, he smiles and nods, ____ that everything is fine.
A．indicated B．indicating C．to indicate D．indicate
