What action should they _____________such a thing happen again?
| A．do stopping | B．do to stop | C．take stopping | D．take to stop |
You must stop and wait for your turn when you see the sign______.
A.
B.
C. 
Mr. Green ____ go to bed ____ he finished his work last night.
A. does; until B. don’t; until C. didn’t; until
when I heard the bad news I couldn’t help ________ .
A. laughing B. dancing C. crying
Kate doesn’t run as ________ as Jim.
A. fast B. fasterC. fastest