[音频]The United States is marking the 14th anniversary of the September 11th 1. _______ _______ . U.S. officials and many other Americans attended observances((宗教的，正式的）仪式； 惯例； 庆祝) Friday to remember those killed and 2. _____ ______ ______ .Nearly 3,000 people died on September 11, 2001 when hijackers used four passenger airplanes to 3. ______ ______ 4. _______ _______ in the United States. In addition to the victims, the 19 hijackers also were killed. Al-Qaeda(基地组织) leader Osama bin Laden（本拉登） and his group 5. _____ _______ ______ the attacks. U.S. forces killed him in a surprise raid on his hiding place in Pakistan four years ago.Friday morning, President Barack Obama, his wife and White House workers 6. _______ a public moment of silence in Washington. They gathered on the White House grounds at 8:46. That was the 7. _______ _______ when a hijacked airplane 8. ________ the World Trade Center.In New York, families of the victims gathered for a ringing of bells and reading of the names of those killed in the terrorist attacks. 9. ________ _____ _______ were held at 8:46 and 9:03 in the morning, when a second hijacked plane also hit the World Trade Center.Near Washington, U.S. 10. _______ _______ Ash Carter and other officials attended an observance at the Pentagon五角大楼, the home of the Defense Department国防部. They joined in 11. ______ ______ _______ when a hijacked airplane hit the Pentagon, killing 184 people.Earlier Friday, a large American flag was hung down the side of the Pentagon, where the passenger jet hit.There also was a moment of silence at 10:03 a.m. That was the time when a fourth hijacked plane 12. _______ in western Pennsylvania. All 44 people on the plane were killed. Many Americans believe the hijackers 13. _____ _____ ____ _____ ____ ______ in the nation's capital.The fourth plane came down in a field in the 14. _______ ________ of Shanksville. Today, a new visitor center there tells the story of the 9/11 attacks. The Flight 93 National Memorial was set up to recognize the passengers and crew members who attacked the hijackers.Stephen Clark is with the U.S. National Park Service. It 15. __________ the visitors center and surrounding grounds."It just 16. ________ me that this aircraft was but 18 minutes away from hitting Washington, D.C."The field was quiet on Friday, very different from the situation 14 years ago.Gordon Felt's brother Edward was one of the passengers on United Airlines Flight 93 on September 11, 2001."It is surreal超现实的，离奇的at times. Early on, it became very 17. ________ to us very quickly that our loved ones, the events surrounding their deaths, had 18. __________ __________ to our country."The last 35 minutes of Edward Felt's life, and others on the plane, are explained at the new visitor center. Relatives hope visitors to the memorial will 19. ________ ______ _____ ______ _____ the actions of their loved ones."They'll get a sense of who those 40 heroes were, as well as what 20 _______ ________ ________ _____ to help save the Capitol building（国会大厦，首都大厦；美国国会大厦） that morning."I'm George Grow.