在硫酸工业生产中，为了有利于SO₂的转化，且能充分利用热能，采用了中间有热交换器的接触室见下图。按此密闭体系中气体的流向，则在A处流出的气体为   

A．SO₂

B．SO₃，O₂

C．SO₂，SO₃

D．SO₂，O₂

In the coming decades, Europe’s influence on affairs beyond its borders will be sharply limited, and it is in other regions, not Europe, that the 21st century will be most clearly forged and defined. Certainly, one reason for NATO’ s increasing marginalization stems from the behavior of its European members. With NATO, critical decisions are still made nationally; much of the talk about a common defense policy remains just that--talk. There is little specialization or coordination. Missing as well are many of the logistical and intelligence assets needed to project military force on distant battlefields. With the Cold War and the Soviet threat a distant memory, there is little political willingness, on a country-by-country basis, to provide adequate public funds to the military.
Political and demographic changes within Europe, as well as the United States, also ensure that the transatlantic alliance will lose prominence. In Europe, the E. U. project still consumes the attention of many, but for others, especially those in southern Europe facing unsustainable fiscal shortfalls, domestic economic turmoil takes precedence. No doubt, Europe’s security challenges are geographically, politically and psychologically less immediate to the population than its economic ones. Mounting financial problems and the imperative to cut deficits are sure to limit what Europeans can do militarily beyond their continent. It is true that the era in which Europe and transatlantic relations dominated U.S. foreign policy is over.