如图，这是泡沫灭火器工作时的模拟实验．请你根据所学物理、化学知识简述其中的工作原

任何商品的替代效应总是为正值，收入效应则根据商品的特点，有的为正值，有的为负值。( )

被称为伊斯兰世界建筑经验的结晶的建筑是（）。

县城竞有如此优秀花旦，真令人意想不到!（）那精湛演技、圆熟唱功，真看不出她是第一次登台演出。而当她一声长叹，背身蓦然往观众座席回眸一顾时，整个现场立刻（），静得听得见针掉地下的声音。

填入括号最恰当的一项是：

A．何况 万籁无声

B．况且 万籁无声

C．何况 鸦雀无声

D．况且 鸦雀无声

EBCT是以下哪种CT的缩写()

A．螺旋CT 

B．CT血管造影 

C．电子束CT 

D．高分辨力CT 

E．普通CT

Which of the following statements about theories of the yield curve is most likely correct（）

A. A liquidity preference cannot be consistent with a flat term structure of interest rates.  B. The liquidity preference theory suggests that a downward-sloping term structure of interest rates is due to investors expecting short-term rates to decline, and although there is a maturity premium to consider, it is not large enough to offset the expectation of declining short-term rates. 

C. The pure expectations theory suggests that an upward-sloping term structure of interest rates is a consequence of investors expecting short-term rates to remain unchanged for a period of time, followed by investors expecting short-term rates to rise for a period of time.