单项选择题 Friendship helps us understand （）we are, （）we need each other and （）we can do for each other.

单项选择题 —The research on the new bird flu virus vaccine is challenging and demanding. Who do you think can do the job — （）my students have a try

单项选择题 —What was your impression of last night's lecture —Speaking（）, I thought it was rather boring.