Most smokers are perfectly aware _____ the danger of smoking.[ ]

Mary never does any reading in the evening ,______.

The time he has devoted in the past 10 years______ the disabled is now considered__________ of great value.

Driving less, walking more is good for our health.–So I’d rather __________ an hour’s walk to work than consider __________a car.

In case of fire, stay low to the ground in a smoky room, ________ smoke always rises towards the ceiling