1．有一個(gè)電子鐘，每走9分鐘亮一次燈，每到整點(diǎn)響一次鈴，中午12點(diǎn)整，電子鐘既響鈴又亮燈，問：下一次既響鈴又亮燈是（　　）點(diǎn)鐘。

2．Students Arn,Bob,Cyd,Dan,Eve,and Fon are arranged in that order in a circle.They start counting：Arn first,then Bob,and so forth.When the number contains a 7 as a digit（such as 47）or is a multiple of 7 that person leaves the circle and the counting continues.Who is the last one present in the circle？（　?。?br />學(xué)生Arn、Bob、Cyd、Dan、Eve和Fon按照這個(gè)順序排成一個(gè)圈。他們開始數(shù)數(shù)：首先是Arn,然后是Bob,依此類推。當(dāng)數(shù)字中含有7這個(gè)數(shù)字（例如47）或是7的倍數(shù)時(shí)，那個(gè)人就離開這個(gè)圈子，計(jì)數(shù)繼續(xù)。誰是圈內(nèi)的最后一個(gè)人？（　?。?/div>

3．Let Z be a 6-digit positive integer,such as 247247，whose first three digits are the same as its last three digits taken in the same order.Which of the following numbers must be a factor of Z？（　　）
設(shè)Z是一個(gè)六位正整數(shù)，例如247247，其前三位數(shù)字與按相同順序取的后三位數(shù)字相同。以下哪個(gè)數(shù)字必定是Z的因數(shù)？