_广西成考网

When will deep snow lead to floods?

• A、The snow suddenly gets frozen.

• B、The top of the ground becomes wet.

• C、I trains hard with a big rise in temperature.

• D、The snowmelt s gradually into a river.

51.          

Before you leave the classroom，_____all the lights.

• A、turn up 

• B、turnover

• C、turn to

• D、turn off