单项选择题
Students should be encouraged to use（）Internet as（）resource.
A./；a B./；the C.the；the D.the；a
单项选择题 One potential danger is（）the information could be used by others to your disadvantage.
单项选择题 This fire extinguisher is to be used only in case of（）
单项选择题 She's part of a team of scientists who are（）upon cancer research.
