单项选择题
A.blue line B.purple line C.dashed blue line D.alternate red and blue line
A.used to measure the speed of wind B.in which the pressure of the air is measured C.that tells which direction a storm is coming from D.used to measure the height of waves
A.it is above 70°F B.the ground over which it moves is cooler than the air C.it originated in a high pressure area D.it originated in a low pressure area