国标规定，单个圆柱齿轮的（）用粗实线绘制。
A、齿顶圆和齿顶线
B、分度圆和分度线
C、齿根圆和齿根线
D、齿顶圆与齿根圆
参考答案：A
Read and choose. （读一读，选择正确答语）
1. — How much is it?
— ______ [ ]
A. It is two yuan.
B. They are ten yuan.
2. — Can I help you?
A. Yes, please.
B. No, it's not.
3. — How much are they?
A. It's eight yuan.
B. They're nine yuan.
4. — What time is it?
A. It's five o'clock.
B. It's rainy.
推动高新技术产业做强做大，要( )
A．引进国外先进技术
B．发挥国家重大科技专项的引领支撑作用
C．实施产业创新发展工程
D．发展民营科技
E．加强财税金融政策支持
