德州市2009年实现生产总值(GDP)1545.35亿元,用科学记数法表示应是(结果保留3个有效数字)
A:1.54×108元
B:1.545×1011元
C:1.55×1010元
D:1.55×1011元
下列各物质中,按熔点由低到高排列正确的是( )
It’s 9:00 in the evening. The family are at home. Jim’s father sits in a chair. He’s watching TV(看电视). His mother stands near the window. She feeds(喂) the birds—Polly. Polly says, “Thanks! Thanks!” Where is Jim? Oh, he’s behind the door. Kate is looking for(找) him. They play games in Kate’s room.
如图甲为人体血液循环示意图,图乙是肺泡与血液之间的气体交换示意图,图丙是尿的形成过程示意图,请据图分析回答下列问题.
下
如图,一张三角形纸片ABC,AB=AC=5.折叠该纸片使点A落在边BC的中点上,折痕经过AC上的点E,则线段AE的长为____ .
(Ⅰ)求频率分布直方图中a的值;
(Ⅱ)估计该企业的职工对该部门评分不低于80的概率;
(Ⅲ)从评分在40,60)的受访职工中,随机抽取2人,求此2人的评分都在40,50)的概率.