下列关于我国可持续发展主要政策措施描述有误的是( )。A．注意保护耕地，合理控制新

一位男士在市区驾车因超速而被警察拦住．警察走过来对他说：“先生，您刚才的车速是90krn/h！”这位男士诡辩道：“不可能的！我才开了7分钟，还不到1小时，怎么可能走了90km呢？”“先生，我的意思是：像您刚才那样开车，您车上的速度计指示的是90km/h．”从物理学角度看，警察向男士阐述的是（　　）

A．瞬时速度

B．平均速度

C．平均速率

D．以上选项均不正确

There is no known_____for this disease but it can be______.

A．cure, treated

B．cured; treat

C．cure; treat

D．treat; cured

彩色多普勒超声显像的仪器调节正确，但血管内彩色信号缺失，主要原因为（）。

A.血管与声束成0°

B.血管与声束成180°

C.血管与声束成120°

D.血管与声束成90°

E.血管与声束成60°

Consider two markets; one has a Herfindahl-Hirschman Index (HHI) of 50, while the other has a four-firm concentration ratio equal to 2%. Which of the following statements most accurately describes these two markets（）

A. Both of these markets are monopolies.

B. The market with the HHI equal to 50 is very competitive, while the other market has low competition.

C. Both markets are highly competitive.

经直接还原生成脱氧核苷酸的物质是

A．核糖

B．核糖核苷

C．一磷酸核苷

D．二磷酸核苷

E．三磷酸核苷