下列哪项不是亚急性细菌性心内膜炎的心脏并发症A．冠心病 B．心脏破裂 C．缩窄性心包

Water is (41) important of all the things we (42) and drink. Not many people understand this, (43) it’s quite true. The human body (人体) can go (44) food for a long time, but two (45) three days without water can usually (46) people die.
Many people don’ t understand how much water the human body needs to work well and many people do not drink (47) , even (48) hot weather.
Our body is (49) water, about 65% to 75%, ff we do not have enough water, we’ll (50) tired and many will get ill. So you see, how important water is to us all.

[A] fall [B] fell[C] feel

方程x=-x的解是______．

纸质干式空气滤清器主要是利用惯性方式滤除空气中的杂质。（）

请演示脊柱的检查方法。

直径为300mm的蒸汽管道，放在剖面为300mm×400mm的砖砌沟中，管道表面的发射率ε₁＝0.74，砖砌沟的发射率ε₂＝0.92，蒸汽管道的表面温度为200℃，砖砌沟的平均温度为80℃，每米蒸汽管道的辐射热损失为( )W。

A．1300～1400
B．1200～1300
C．1400～1500
D．1100～1200