题目

. Not until _______ smoking ________ healthy lungs.   A. did he five up, he had                     B. did he give up, did he have   C. he gave up, he had                        D. he gave up, did he have 答案：D19．如图所示，用轻质活塞在气缸内封闭一定质量的理想气体，活塞与气缸壁之间的摩擦忽略不计．开始时活塞距气缸底的高度为h1=0.50m，气体温度为t1=27℃．给气缸加热，活塞缓慢上升到距气缸底的高度为h2=0.80m处时，缸内气体吸收Q=450J的热量．已知活塞横截面积S=5.0×10-3m2，大气压强P0=1.0×105Pa．求：①加热后缸内气体的温度．②此过程中缸内气体增加的内能△U．