扑灭精密仪器火灾，主要用（）灭火器。
A、二氧化碳和一氧化氮
B、二氧化碳和1211
C、一氧化碳和1211
D、二氧化碳和干粉
参考答案：B
一条弦把圆的一条直径分成2cm和6cm两部分，若弦与直径所成的角为30°，则圆心到弦的距离为______．
Which of the following nursing diagnoses would be most appropriate when teaching the mother of a toddler()
A. Activity intolerance.
B. Risk for injury.
C. Delayed growth and development.
D. Impaired mobility.
