It is every citizen’s duty to go out to ______ the snow on the street______ it stops falling so as to make it convenient for traffic to pass. . 

It is every citizen’s duty to go out to ______ the snow on the street______ it stops falling so as to make it convenient for traffic to pass. . 

It is every citizen’s duty to go out to ______ the snow on the street______ it stops falling so as to make it convenient for traffic to pass.

1. A.
   sweep up; the instant
2. B.
   clear up; the moment
3. C.
   clean up; immediately
4. D.
   whirled up; directly

It is every citizen’s duty to go out to ______ the snow on the street______ it stops falling so as to make it convenient for traffic to pass．

A．sweep up; the instant                                 B．clear up; the moment

C．clean up; immediately                       D．whirled up（卷走）; directly