阅读理解

    Tom,Bill and Dave lost their backpacks．They are at the lost and found office．The backpacks are the same(相同的),but the things in them are different．Can you help them find the right(正确的)backpack?

    Tom：I have a  maths book and a pencil case in my backpack．There are three pencils,a pen and an eraser in the pencil case．

    Bill：I have a Chinese dictionary,a maths book and two notebooks in my backpack．

    Dave：There are two CDs,three picture books in my backpack．My English book is also in it．

我国保护未成年人合法权益的专门法律有（  ）

某物理兴趣小组制成了一个潜水艇模型．已知模型重10N；完全浸没时受到的浮力是12N，要使模型完全浸没水中，应往模型中注入的水重至少要____ N；当潜水艇模型在水中匀速直线下潜时受到的合力是____ N，潜水艇在下潜过程，受到水的压强将变____ 

图中，适宜在P点布局的工厂是（　）