我国国有经济起主导作用，主要体现在（）。
A.国有经济在各经济成分中占的比重较大
B.国有经济控制国民经济命脉
C.国有经济在各行业都起主导作用
D.国有经济比重应不断提高
参考答案：B
解析：国有经济起主导作用，主要体现在控制力上，对关系国民经济命脉的重要行业和关键领域，国有经济必须占支配地位；在其他领域，可以通过资产重组和结构调整，以加强重点，提高国有资产的整体素质。
| A pilot cannot fly a plane by sight alone. In many conditions, such as flying at night and landing in dense fog, a pilot must use radar, an alternative way of navigating. Since human eyes are not very good at determining speeds of approaching objects, radar can show a pilot how fast nearby planes are moving. The basic principle of radar is exemplified by what happens when one shouts in a cave. The echo of the sounds against the walls helps a person determine the size of the cave. With radar, however, the waves are radio waves instead of sound waves. Radio waves travel at the speed of light, about 300, 000 kilometers in one second. A radar set sends out a short burst of radio waves: Then it receives the echoes produced when the waves bounce off objects. By determining the time it takes for the echoes to return to the radar set, a trained technician can determine the distance between the radar set and other objects. The word "radar," in fact, gets its name from the term "radio detection and ranging." "Ranging" is the term for detection of the distance between an object and the radar set. Besides being of critical importance to pilots, radar is essential for air traffic control, tracking ships at sea, and for tracking weather systems and storms. |
According to the passage, what can a radar detect besides location of objects
A．Size.
B．Weight.
C．Speed.
D．Shape