— Which of these two books will you take?—I will take ______ in case the trip is boring.
If the dog hadn't woken us, we wouldn't have noticed the fire and it __________ to the house next door.
As civilization __________,more and more people have realized the importance of preserving rare animals from dying out.
Was it __________ the inter-national conference that made the city the focus of this area?
-Why are you so late?-We were __________ by the terrible traffic.
With more people __________ the traffic rules, our city is becoming better organized.