It suddenly occurred to me I hadn’t locked my door．
A．which B．where
C．that D．whether
I still remember _______ the grand school used to be a abandoned airport two years ago.
A. how B. where
C. when D. why
I didn't understand _______it meant to him until I was in his place.
A. what B. that
C. how D. which
won’t change my belief _________ success comes to those who act．
A．that B．which
C．where D．how
No one knows for certain how the first Americans arrived in _____ is now the United States.
A. which B. what
C. where D. why
Tom’s most positive quality is _____ he’s very outgoing.
A. that B. why
C. how D. whether
