某校九年级进行了模拟考试后，张老师对九（2）班全体同学“满分值为6分得一道解答题的得分”情况进行了统计，绘制成下表（学生得分均为整数分）：

由于在填表时不慎把墨水滴在表格上，致使表中数据不完整，但已知全班同学此题的平均得分为4分，结合上表回答下列问题：

（1）九（2）班学生共有多少人？

（2）若本年级学生共有540人，请你用此样本估计整个年级有多少同学此题得满分？

如图是运动员顶足球时的情景，忽略空气阻力，下列说法正确的是（　　）

北京自1984年开展大气监测，至2012年底，全市已建立监测站点35个.2013年，北京发布的首个PM_2.5年均浓度值为89.5微克/立方米．2014年，北京空气中的二氧化硫年均浓度值达到了国家新的空气质量标准；二氧化氮、PM₁₀、PM_2.5年均浓度值超标，其中PM_2.5年均浓度值为85.9微克/立方米．2016年，北京空气中的二氧化硫年均浓度值远优于国家标准；二氧化氮、PM₁₀、PM_2.5的年均浓度值分别为48微克/立方米、92微克/立方米、73微克/立方米．与2015年相比，二氧化硫、二氧化氮、PM₁₀年均浓度值分别下降28.6%、4.0%、9.8%；PM_2.5年均浓度值比2015年的年均浓度值80.6微克/立方米有较明显改善．（以上数据来源于北京市环保局）

根据以上材料解答下列问题：

    When I was in the ____ (九) grade, luckily, I was chosen to be the princess in the school play. For weeks my mother had helped me practice my lines. But ____ (一旦) on the stage, every word disappeared from my head. Then my teacher asked me to change my role to be a narrator (解说者) for the play.

    ____ (尽管) I didn't tell my mother what had happened that day, she noticed my unhappiness. She asked if I wanted to take a walk in the garden.

    It was a lovely spring day. We could see several dandelions (蒲公英) ____ (在…中间) the grass. I watched my mother bend down by one of the dandelions. "I think I'll dig up all these weeds (野草)," she said. "From now on, we'll only have roses in this garden."

    "But I like dandelions," I disagreed. "All flowers are beautiful-even dandelions!"

    My mother looked ____ (严肃地) at me. "Yes, every flower gives pleasure in its ____ (自己的) way, doesn't it?" she asked thoughtfully. I nodded. "And that is true of people, too," she added.

    When I ____(意识到) that she had guessed my pain, I started to cry and told her the ____ (真相). "But you will be a wonderful narrator," she said, reminding me of how much I loved to read stories aloud.

    Thanks to my mother's encouragement, I got to know everybody had his or her ____ (价值) in the world. I felt ____ (骄傲的) of the role in the play.