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Dear Jenny,

    How's it going? Are you busy with your study these days?

    I've been back at school 1nearly four weeks. I'm very glad to tell you that great 2have taken place in our school this term. First of all, we're asked to “clear ourplates” when having our meals and say3 to wasting. Some of us used to order more than what we could eat. That was a big waste of food. Now we need to4 the food we order. We should also stop wasting in some other ways. For example,we should turn off the lights when we 5 the classroom. And our school has opened up some fields for us to learn how to grow vegetables. Each class is given a small garden and our class has decided to grow some tomatoes and beans(豆类) in our6 time. I think that'll be very interesting. Maybe I'll be able to 7 you some beans we've grown by ourselves next time! What's more,we have only two classes in the afternoon 8 we have more time for after school activities. I'm one of the traffic safety volunteers in our school. After school, we take turns to go to the streets near our school and ask people to 9 the traffic rules.

    I think we are having a different school life now!

    Please write back soon and tell 10 more about your school.

Yours,

Wang Wei

从南极到北极，纬度变化规律是（    ）

在平面直角坐标系中，点A （ 5，3 ） 的坐标变为 （ 3，﹣1），则点A经历了怎样的图形变化（   ）

如图，点C是半圆O的半径OB上的动点，作PC$\perp$AB于C．点D是半圆上位于PC左侧的点，连结BD交线段PC于E，且PD=PE．

(1) 求证：PD是⊙O的切线．
(2) 若⊙O的半径为$4\sqrt{3}$,PC=$8\sqrt{3}$,设OC=x,$P{D}^2=y$．
①求关于的函数关系式．
②当$x=\sqrt{3}$时，求$\tan B$的值．

目前，我国登记在册的吸毒人员总数已增加到100万人，其中青少年占74%．对此有关部门强调，禁毒工作将继续以在校中小学生和高危人群为重点。对此，你认为青少年应做到（    ）

①积极配合，做好毒品预防宣传工作                                            ②只要不上瘾吸几口也无妨

③用合适的手段，积极同吸毒、贩毒、制毒行为作斗争            ④要珍爱生命、自觉远离和拒绝毒品