A:(﹣∞,0
B:﹣2,2
C:(﹣∞,2
D:0,2
_________ he was exercising in the park yesterday morning, he found a purse under the tree.
在测量空气的相对湿度时,为了减小误差,提高测量数据的可靠性,应该反复测量多次,取____ 值.
分母是100的分数都是百分数。