A．the possibility of the building collapsing.
B．the likely explosion from the gas tank.
C．the possible subsequent rockslides.        
D．the noise and trembling at the moment.

A．An hour before sunset.
B．An hour after sunset.
C．An hour before sunrise.
D．An hour after sunrise.

A．The space shuttle would be under close inspection.
B．One of the crew members failed to head home.
C．Unexpected weather delayed the landing of Endeavor.
D．The space shuttle made a smooth landing.