---In the countryside you can enjoy fresh air, blue sky and quiet surroundings.---_______ more and more retired people are escaping from the crowded city.

 — How many students are going to the Great Wall? — ____.

(2011·北京高考)The employment rate has continued to rise in big cities thanks to the efforts of the local governments to increase________.

In American there are more households with pets than ______ with children.

＿＿＿＿four years since I joined the army.