______ a jacket. It's cold outside.
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All guests must_______ at the front desk.
A. signing in
B. sign in
C. signed in
_______ leave! We haven't finished yet.
A. Don't
B. Not
C. No
_______ careful! You almost spilled coffee on me.
A. Being
Be
C. Not be
_______ this medicine before you go to bed, OK?
A. Taking
B. To take
C. Take