直径小于或等于2.5微米的颗粒物又称作PM2.5，也称为细颗粒物或可入肺颗粒物，相当于头发丝直径的$\frac{1}{20}$，可直接进入肺部，以室内PM2.5为85微克/立方米，轻度污染指数为130（轻度污染）计算，则每天吸入鼻孔，咽喉，肺及血液里的有毒颗粒物和有害气体总数约为850毫克，若1千克=1000000毫克，则850毫克用科学记数法可记作（　　）

根据下面的对话情景，在每个空白处填上—个适当的句子，使对话的意思连贯、完整。
A:I have a piece’ of good news to tell you , May?
B：Oh，____ ?
A: A new library has been open in our city, and there are many books there.
B: Really? ____ ?
A: It is open at 8:00 in the morning and closed at 6:00 in the afternoon.
B: ____ ?
A:  Yes, I went there yesterday
B: ____ ?
A: It’s in No. 7 building,  Center Street. ____ ?
B:Yes. I want to go there tomorrow.  Would you like to go with me?
A: Of course. Let’s meet at our school gate tomorrow.
B：OK. See you.
A: See you.

如图正方形代表太平洋，图中圆点代表中国，最能反映中国位置的是（　　）