. ____ by the thought that she was suffering a heart attack, she screamed for help.
. Medical ______ shows that men are more likely to have heart attacks than women.
. Several years had passed ______ I finally realized the true value of friendship.
. All passengers ______, please fasten your seat belts and remain seated ______ the plane is landing.
. Unfortunately, it was in Yushu County, ______ a 7.1-magnitude earthquake happened on April 14, 2010, ______ a large number of students were buried inside damaged schools.
. ______ World Exposition in 2010 is the first registered World Exposition in ______ developing country.