keep away
使离开,使站开
keep out
关在门外；不准入内
to keep the smoke out
不让烟进来
This coat keeps out the wind.
这大衣挡风.
keep off
避开；不接近
Keep off the grass!
请勿践踏草地!
My doctor has warned me to keep off sugar.
我的医生劝我别吃糖.
Keep your dog off me.
把你的狗从我这儿拿开!
"Keep off oil, or else it will perish your rubber boots."
"不要碰油,否则会把你的橡胶鞋弄坏的."
keep on
继续；保持
He just kept on writing.
他正在继续写.
keep up
继续；坚持
If this rain keeps up the garden will be ruined.
如果这雨继续下,花园就完蛋了.
保持；维持
The high cost of materials keeps up prices.
材料的昂贵费用使价格居高不下.
Keep your chin up!
不要气馁!;不要灰心!
综合以上内容,不难发现正确答案为C.