Don’t bother me．I am listening to the birds ______．

______ to nuclear radiation, even for a short time, may influence genes in human bodies.

－It’s necessary to limit the speed of electric bikes.－Yes, most riders of electric bikes in China        40-50 kilometers per hour often ignore red lights,        the risk of traffic accidents. 

 It was freezing last night, so they had the fire___ all night long.

The boy wanted to ride his bicycle in the street, but his mother told him_________.