放射治疗病人喉源性呼吸困难Ⅲ度以上者宜作紧急气管切开。
参考答案:对
58. The little boy has learned many Tang dynasty poems _____ though he is very young.
A.by heart
B.by mind
C.by the way
D.by book
用化学方程式解释下列反应事实
(1)有黑色固体生成的化合反应______;
(2)过氧化氢溶液和二氧化锰制取氧气______
(3)“白加黑”产生人类须臾离不开的单质______.