论述历史上经济重心逐渐南移的过程及其对中国社会的影响。

It's hot _____________ summer in Beijing. [ ]

A. by

B. on

C. at

D. in

[问题2] Flash是一种矢量图形编辑和动画制作软件，主要应用于页面设计和多媒体创作等领域。请说明在多媒体应用中，矢量动画的特点。

在下列哪种社会中，家庭发生的作用最大( )

A．融合模式
B．棱柱模式
C．衍射模式
D．过渡模式

Questions 10—11 are based on the following:
Antinuclear activist: The closing of the nuclear power plant is a victory for the antinuclear cause. It also represents a belated acknowledgment by the power industry that they cannot operate such plants safely.
Nuclear power plant manager: It represents no such thing. The availability of cheap power from nonnuclear sources, together with the cost of mandated safety inspections and safety repairs, made continued operation uneconomic. Thus it was not safety considerations but economic considerations that dictated the plant’s closing.

Which one of the following, if true, most ply supports the activist’s claim of victory

A．The plant had reached the age at which its operating license expired.

B．The mandate for inspections and repairs mentioned by the manager was recently enacted as a result of pressure from antinuclear groups.

C．The plant would not have closed if cheap power from nonnuclear sources had not been available.

D．Per unit of electricity produced, the plant had the highest operating costs of any nuclear power plant.

E．(E) The plant that closed had been able to provide backup power to an electrical network then parts of the network became overloaded.