[填空题]

America obviously can’t prevent other countries from ______.

[填空题]The drugs used to prevent migraines can block the______ effects , which may cause the blood vessels to expand.

[填空题]In America and many other countries, one special kind of box contains the future. It’s called a ballot box. What people put into the box on Election Day can change the course of history.
Elections are the (36) of a democracy. The word democracy (37) means "the people rule", an important (38) in America’s history. In America, elections are held every two years for members of Congress. In these elections, all seats in the House of Representatives and one-third of the Senate seats are up for grabs. Every four years, voters go to the polls to (39) the nation’s president and vice-president. Voters also regularly vote for state and city government leaders and local school board members.
In the American electoral system, people don’t really vote for presidential candidates. Instead, voters (40) their ballots for "electors" who support each candidate. Each state has as many electors as the (41) number of its repres

[填空题]America also borrows culture from other countries therefore its influence is not a ______ traffic.

[填空题]The balance of nature can prevent soil deterioration.

[单项选择]What can be done to prevent swine flu
A. Stop touching mouth, nose or eyes.
B. Avoid using tabletops and telephones.
C. Prevent people from taking buses.
D. Wash hands and keep social distanc

[单项选择]With inspiration from other food cultures, American food culture can take a ______ for the better.
A. share
B. chance
C. turn
D. lead