酸的当量=酸的分子量/酸分子中被金属置换的氢原子数。()
参考答案:对
He was stopped by the rain the trees.[ ]
A. to plant
B. to planting
C. for planting
D. from planting
异步电动机额定电压为1000V以下,常温下绝缘电阻不应低于()。