校长负责制的性质是（）
A.个人负责制
B.集体负责制
C.三位一体制
D.集体领导与个人负责结合制
参考答案：A
句型转换
She spoke louder so that she could be heard by people at the back of the big hall.
She spoke louder by people at the back of the big hall
若汽包液位不稳定，则（）
A、对蒸汽压力无影响，对水碳比有影响
B、影响水碳比，但对蒸汽压力无影响
C、自产蒸汽压力不稳
