On April 14, 2010, many people dressed in black with white flowers ______ their chests observed three minutes of silence in memory of the victims in Yushu Earthquake .
The e-mail, as well as the telephone, ______ an important part in daily communication.
Jumping out of ______airplane at ten thousand feet is quite _____exciting experience.
What they need ______ enough money, while what we need ______ enough workers.
– Do you know William failed the exam, Jenny? -- _____? As far as I know, he is always working hard.
When you communicate with people, it is not unusual to find yourself in a situation ____ you have to politely decline an offer.