中压燃气管道的管壁外缘两侧（）米范围内的区域应确定为中压燃气管道的安全保护范围。
A、0.5
B、1.0
C、1.5
D、2.0
参考答案：B
（x+1）2-6（x+1）+5=0．
Annie Jump Cannon, ________ discovered so many stars that she was called "the census taker of the sky".
A．a leading astronomer,
B．who, as a leading astronomer,
C．was a leading astronomer,
D．a leading astronomer who
