电子商务环境下，影响网上购物的主要障碍是网上购物的（）和可靠性。
A.便捷性
B.可用性
C.安全性
D.透明性
参考答案：C
改错题。
One cold winter day in 1900, a small boy calling 1.________
Charlie Chaplin walking along the street in London. 2.________
He did not have breakfast and lunch. He wanted to 3.________
buy some bread, and he didn't have any money. 4.________
His father dead when he was very young. His 5.________
mother was often very sick, and she could not take 6.________
care of Charlie or his brother. All of them had to 7.________
work to help their sick mother.
He was a small boy but his dream was not very big. 8.________
He wanted to be great man in the world of film. So 9.________
he worked very hard to sing and danced well. 10.________
牙槽突裂植骨术后拆线时间是
A．5天B．7天C．8天D．9天E．10～14天
