英镑大幅贬值。There was a sharp fall in the value of the pound.直到现在，美元的贬值似乎都无法想象。Until now, a devaluation of the dollar seemed inconceivable.这将会造成数种欧洲货币的贬值。It will lead to devaluation of a number of European currencies....
First, why do we get light propagating at all?首先, 我们来看看光为什么可以传播?The model shows a wave propagating from left to right through air.该模型表明,波从左至右通过空气.What are the pigeons doing outside? Eating, sleeping, propagating!门外的那些鸽子在...