Miss White see some school things ____the teacher's desk. They are a pencil box, a red pencil, two black ____(pen), a blue watch and an ____ notebook. Whose are they?

    Miss White asks Tina, “Tina, is this ____pencil box?”Tina says, “Yes, it is. Thank you.” “Are____(this) your pens?” asks Miss White. “No, they ____.They're____(Lucy).” says Tina.

Miss White goes to Lucy and says, “ Are they your pens, Lucy?” Lucy says, “Yes, they are. Thank you.” “What____ the red pencil? Is it ____(you), too?” Miss White asks. “ No, it isn't.” says Lucy. “And the watch and the aren't mine, either(也).” “Oh, I can put them____the lost and found box.” says Miss White.

Don't worry. I'll ____ (think about, think of) a way.

如图，两个正方形的面积分别为16，9，两阴影部分的面积分别为a，b（a＞b），则（a﹣b）等于（　　）