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.

A、 motionless
B、 massive
C、 flexible
D、 noticeable

【正确答案】 A

【答案解析】[解析] 本题中，stationary的意思是“固定的”。A项“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。