he forward a class trip?
A:Is; looking; to have
B:Does; look; having
C:Is; looking; to having
D:Does; looking; to having
x2+kx+9是完全平方式,则k=____
读图,我国7月等温线分布图,完成下面小题
气缸长为L=1m(气缸厚度可忽略不计),固定在水平面上,气缸中有横截面积为S=100cm2的光滑活塞封闭了一定质量的理想气体,已知当温度为t=27℃、大气压强为p0=1×105 Pa时,气柱长为L0=0.4m.现用水平拉力向右缓慢拉动活塞,求:
①若拉动活塞过程中温度保持为27℃,活塞到达缸口时缸内气体压强;
②若活塞到达缸口时拉力大小为500N,求此时缸内气体温度为多少摄氏度.