计数长度是指从起点到终点某拖板移动的距离。

On initial assessment of a 7-year-old with rheumatic fever, which of the following would require the nurse to contact the physician immediately

A. Heart rate of 150 bpm.
B. Twitching in the extremities.
C. Red rash on the trunk.
D. Swollen and painful knee joints.

打钟时，我们听到的钟声是由于 ______产生的，我们听到的钟声是靠 ______来传播的．

统计学检验的无效假设应是

A．H₀:p₁=p₂=p₃=p₄=p₅

B．H₀:p₁=p₂=p₃=p₄＞p₅

C．H₀:π₁=π₂≠π₃=π₄=π₅

D．H₀:π₁≠π₂≠π₃≠π₄≠π₅

E．H₀:π₁=π₂=π₃=π₄=π₅

脑的供血主要来自（）。

A.大脑前动脉

B.大脑中动脉

C.大脑后动脉

D.颈内动脉

E.基底动脉

巷道材料存放标准是什么？