请根据所给的汉语或首字母提示填写单词，完成句子。

1．It’s known that Obama was e_________ president of the United States.

2．Look! The sign reads: “Parking is f__________. ”We had better find somewhere else to park our car.

3．Mum won’t be at home for a f___________, that is, I will have to be alone for 14 days.

4．The first settlers struggled to earn their living in spite of great h___________.

5．An a__________ is a flying machine of any type, with or without an engine.

6.They set aside enough money to live in c__________ （舒适）after retirement.

7．Unless you spend _____________（合理的） time together, talking on the phone, writing letters, friendship will die out.

8．Shanghai is in __________（准备，筹备）for World Exposition in 2010．

9．The government promised to offer an _____________（充裕的，丰富的）supply of fund to fight against financial crisis.

10．In UK, students are encouraged to ___________（参与）in social activities.