The small shop ________ for several years.
A：opened
B：has been opened
C：has opened
D：has been open
—Hello, may I speak to Mr Green , please?—Sorry. He ________ a meeting. Can you call him later?
我会解词。
①亢奋：____
②冗杂：____
③叹为观止：____
④戛然而止：____
6____7=13
设函数f（x）=xm+ax的导函数f′（x）=2x+1，则数列{ 1f(n) }（n∈N*）的前n项和是（ ）
