1.assumption的基本意思是“假定,臆测”,多指无根据的设想; 其后可接that引起的同位语从句,从句中谓语动词可用虚拟式。
2.assumption的另一个意思是“担任,承担”,多与介词of连用。

Don't rely on the information she gave you; it is pure assumption.不要相信她告诉你的消息,那完全是臆测。
The theory is bottomed on questionable assumptions.这一理论是建立在靠不住的假设基础上的。
The army's assumption of power is very fierce.军队的夺权相当激烈。
We mistook assumption that the price would fall.我们错误地认为价格会下降。