比较两组均数相差很大数据的离散程度大小的指标应选用()
A.极差
B.四分位数间距
C.标准差
D.变异系数
E.方差
参考答案:D
男性患者,78岁,夜间睡眠中憋醒,气喘不能平卧,神志淡漠,手脚冰凉,急诊作心电图示广泛前壁心肌梗死。查体:血压70/40mmHg,心率120/min,可闻及室性奔马律。低血压的最可能原因是()
A.低血容量性休克
B.心源性休克
C.急性左心衰竭
D.心律失常
E.急性脑血管意外
Like many other aspects of the computer age, Yahoo began as an idea, (1) into a hobby and lately has (2) into a full-time passion. The two developers of Yahoo, David Filo and Jerry Yang, Ph. D candidates (3) Electrical Engineering at Stanford University, started their guide in April 1994 as a way to keep (4) of their personal interest on the Internet. Before long they (5) that their homebrewed lists were becoming too long and (6) . Gradually they began to spend more and more time on Yahoo.
During 1994, they (7) yahoo into a customized database designed to (8) the needs of the thousands of users (9) began to use the service through the closely (10) Internet community. They developed customized software to help them (11) locate, identify and edit material (12) on the Internet. The name Yahoo is (13) to stand for "Yet Another Hierarchical Officious Orale", but Filo and Yang insist they selected the (14) because they considered themselves yahoos. Yahoo itself first (15) on Yang’s workstation, "akebono", while the search engine was (16) on Filo’s computer, "Konishiki".
In early 1995 Marc Andersen, co-founder of Netscape Communication in Mountain View, California, invited Filo and Yang to move their files (17) to larger computers (18) at Netscape. As a result Stanford’s computer network returned to (19) , and both parties benefited. Today, Yahoo (20) organized information on tens of thousands of computers linked to the web.
5()
A.founded
B.found
C.argued
D.reported