当坐骨结节间径＜8cm时，需加测下列哪个径线A．对角径 B．出口后矢状径 C．骶耻外

图中OP表示价格，OQ表示供给量和需求量，D是需求曲线，S是供给曲线。当市场某商品价格处于P₁时（ ）

①该商品的替代品需求量增加 

②该商品处于卖方市场 

③该商品价格上涨，需求量增加 

④该商品价格上涨，供给量剩余

A．①②

B．①④

C．②③

D．②④

用恰当的词语填空，完成对话。每空一词。

(An Old lady is coughing. She looks weak.)

Kangkang: Good morning, Granny. What's wrong with you?

Granny: Oh, boy. It's difficult for me to 1______.

Kangkang: How 2______ have you been like this?

Granny: I've been like this 3______ last week.

Kangkang: Have you seen a doctor?

Granny: No, I haven't. The chemical factory produces terrible gas. The bad air makes my chest 4______.

Kangkang: That's too bad. Pollution causes too many problems. I think I should write to the newspaper

                about these problems. But now you'd 5______ see a doctor.

19、有两颗人造地球卫星，它们的质量之比为，运行速度之比为，则它们的轨道半径之比    ，周期之比     。 

作为化工生产操作人员应该（）。

A、按照师傅教的操作

B、严格按照操作规程进行操作

C、按照自己的理解操作

D、随机应变操作

纳氏试剂法测定氨氮，加入酒石酸钾钠可消除钙镁和金属离子干扰。