二尖瓣关闭不全术后哪一种情况处理上十分困难()A．周围血管痉挛，左室后负荷加大 B．

家禽人工孵化的条件有哪些？

下列说法中错误的是 [ ]

A．冰比水轻，能浮在水面上                      

B．水结成冰是化学变化

C．标准状况下，水的凝固点为0℃，沸点是100℃   

D．通常状况下，纯水是无色透明的液体

肺的换气是通过什么方式实现的    [ ]

A．呼吸运动 

B．吸气  

C．呼气  

D．气体扩散

测量直流电压和电流时，要注意仪表的极性与被测量回路的极性一致。

In its short history, the art of motion pictures has frequently undergone change that seemed fundamental, () the introduction of sound.

A. such as which resulting from

B. such as that what results from

C. such as that resulting from

D. such as which results from