题目

—When ________ your father start work?—At 8:00 in the morning. A . has B . does C . do D . is 答案：B如图所示，把同样大小的黑色棋子按照规律摆放在正方形的边上：则第4个图形需要黑色棋子的个数是________个，第n个图形需要黑色棋子的个数是________．