【单选题】、这座135米高的巨型灯塔屹立了1000多年之久才被地震所毁;从公元前281年建成点燃起,直到公元641年阿拉伯伊斯兰大军征服埃及,火焰才熄灭。它日夜不熄地燃烧了近千年,这是人类历史上火焰灯塔所未有过的。这座灯塔是( )
【单选题】加工中心在铣削加工一个XY平面上的圆弧时,圆弧起点在(30,0),终点在(-30, 0),半径为50,圆弧起点到终点的旋转方向为顺时针,则铣削圆弧的指令为()。
A.
G18 G90 G02 X-30.0 YO R50.0 F50
B.
G17 G90 G03 X-30.0 YO R-50.0 F50
C.
G17 G90 G02 X-30.0 YO R-50.0 F50
D.
G18 G90 G02 X30.0 YO R50.0 F50
【多选题】加工中心在铣削加工一个XY平面上的圆弧时,圆弧起点在(30,0),终点在(-30,0),半径为50,圆弧起点到终点的旋转方向为顺时针,则铣削圆弧的指令错误的为( )。
A.
G18 G90 G02 X-30.0 Y0 R50.0 F50
B.
G17 G90 G03 X-300.0 Y0 R-50.0 F50
C.
G17 G90 G02 X-30.0 Y0 R50.0 F50
D.
G18 G90 G02 X30.0 Y0 R50.0 F50
【多选题】关于金融诈骗案的特点,下列说法正确的有( )。
【判断题】Winston Churchill was born to an aristocratic family, and got education at Harrow school.
【判断题】Winston Churchill was born to an aristocratic family, and got education at Harrow School.
【单选题】British wartime prime minister Winston Churchill ____ the reporting for 50 years of an UFO incident because of fears it could create mass panic.
【判断题】RGB色彩模型是加色系统,常用于发光体。( )