粉尘在空气中被吸入肺内几率主要取决于其() A.分散度高低 B.比重大小 C.荷电数 发布时间:2017-08-06 22:19 │ 来源:www.tikuol.com 题型:单项选择题 问题: 粉尘在空气中被吸入肺内几率主要取决于其()A.分散度高低B.比重大小C.荷电数量多少D.形状类别E.以上都不是
题型:单项选择题 Situated on the southeast China coast,Fujian Province is separated by_________180—km strait from Taiwan,__________largest island in China.A.不填; theB.a; theC.a;不填D.the;a 查看答案
题型:单项选择题 Our classroom is very clean. Do you know who__cleaned it﹖A.was it thatB.it was thatC.was it who D.he was 查看答案
题型:单项选择题 将一个生鸡蛋放进盛有清水的杯中,鸡蛋下沉至杯底,如图(甲)所示.向水中加适量盐并使其溶解,鸡蛋恰好处于悬浮状态,如图(乙)所示.继续加盐并使其溶解,鸡蛋处于漂浮状态,如图(丙)所示.三种状态下鸡蛋受到的浮力分别为F甲、F乙、F丙,则F甲、F乙、F丙的关系为A.F甲<F乙<F丙B.F甲<F乙=F丙C.F甲=F乙>F丙D.F甲>F乙>F丙 查看答案