题目

— ____________?— I'm looking for a pair of shoes for my son. A . How is it going B . Who's that speaking C . What can I do for you D . Where do you want to go 答案：C1．匀速上升的氢气球和吊篮总重150N，受到的空气浮力（浮力的方向始终是竖直向上）为180N．求：（1）在这一过程中氢气球和吊篮受到的合力是多少？（2）氢气球和吊篮受到的空气阻力是多少？