患者，男，55岁，突然出现两眼向右侧凝视，右侧中枢性偏瘫，病变部位在（）
A.左侧额叶
B.右侧额叶
C.左侧内囊
D.右侧脑桥
E.左侧脑桥
参考答案：E
两组数据作均数差别的t检验，其自由度为（）。
A.n1+n2
B.n1-n2
C.n1+n2-1
D.n1+n2-2
E.n1+n2-3
He__________from his seat and answered the question__________by the teacher.
A．raised; rose
B．raised; risen
C．rose; raised
D．risen; raised
