简述地图上色彩的作用有哪些?
参考答案:
①色彩的运用简化了图形符号系统;
②丰富了地图内容;
③提高地图内容表现的科学性;
④改善地图语言的视觉效果;
⑤提高地图的审美价值。
一绳长为L的单摆,在平衡位置正上方的P处有一个钉子,如图2所示,这个摆的周期是
A.
B.
C.
D.
Haydy went to work at the court of a prince in eastern Austria, _____ he became a director of music. [ ]
A. which
B. that
C. where
D. when