题目

（本小题满分12分，（I）小问5分，（II）小问7分） 在数列中，=1，，其中实数。 求的通项公式； 若对一切有，求c的取值范围。 答案：答案 What a table!I've never seen such a thing before．It is________ it is long． [　　] A．half not as wide as B．wide not as half as C．not half as wide as D．as wide as not half