为了了解江城中学学生的身高情况，随机对该校男生、女生的身高进行抽样调查，已知抽取的样本中，男生、女生的人数相同，根据所得数据绘制成如图所示的统计图表．

根据图表中信息，回答下列问题：

（1）在样本中，男生身高的中位数落在____ 组（填组别序号），女生身高在B组的人数有____ 人；

（2）在样本中，身高在150≤x＜155之间的人数共有____ 人，身高人数最多的在____ 组（填组别序号）；

（3）已知该校共有男生500人，女生480人，请估计身高在155≤x＜165之间的学生约有____ 人.

阅读下列短文，从下面每小题的A、B、C、D四个选项中选出最佳选项。

    What's it all about?

    OneSmallDeed.com is a website which lets the world know the good deeds（行动）they have done and to encourage others to do the same.

    Who are we?

    We are not a big organization, but just a group of people who wanted to find a way to make the world a nicer place. We live in London and come from different countries and cultures. The one thing we have in common is that we are kind and giving people who want to see more people like us.

    Want to join?

    All you need to do is just a small good deed as often as you can do. If you want to encourage others, then post your deeds on our website.

    Here are some suggestions for you to get started:

    1  Open the door for someone 

    2  Give up your seat on the train or bus for someone who needs it more than you.

    3  If somebody asks for your help and you are really busy, find a way. 

    4  If someone in need, like a man in a wheelchair to get across the street, help them. 

    5  If you see someone crying, ask if you can help.

用一句话概括下面这则新闻的主要内容，不超过20个字。

    杭州的建筑工地每年有1 000多个，如果把这些工地的围墙适当“美容”一下，它将成为街头一道独特的风景。为进一步打造“国内最清洁城市”，今后，杭州新开工的建筑工地的围墙都要美化。

现在不少城市的墙绘主要是广告，而杭州的墙绘则比较有江南特色，有些还融入了地域文化。有关部门要求杭州建筑工地的墙绘今后消除盈利性广告，逐步走向公益化，赋予其丰富的文化内涵，体现出杭州的文化特质。

如图，AB是半圆O的直径，AC为弦，OD⊥AC于D，过点O作OE∥AC交半圆O于点E，过点E作EF⊥AB于F，若AC=4，则OF的长为（　　）