convections 发音 US 释义与例句 n. 1. plural of convection 相关短语 gravitational convections forced convections free convections natural convections Rayleigh-Bénard convections forced convection [化] 强制对流 free convection [化] 自由对流 natural convection [化] 自然对流 gravitational convection Rayleigh-Bénard convection