题目

Hopefully in 2025 we will no longer be e-mailing each other, for we _______ more convenient electronic communication tools by then. A . have developed B . had developed C . will have developed D . developed 答案：C一个充氦气的飞艇如图所示，体积为1.5×105m3，空气的密度为1.29kg/m3，氦气的密度为0.18kg/m3，（取g=10N/kg）求：（1）飞艇在空气中受到的浮力是多少？（2）飞艇最多可以搭载多重的物体？