单选题
The prevailing wind is the wind direction most often observed during a given time period. Wind speed is the rate at which the air moves past a
stationary
object.
【正确答案】
A
【答案解析】解析：本题中，stationary的意思是“固定的”。A项的motionless“不动的”符合题意，如：The cat sat motionless．(这只猫蹲着不动。)其他三项massive“厚重的”， flexible“灵活的”，noticeable“显而易见的”都不正确。