下列说法正确的是( )
A.平面上三点确定一个圆
B.以两条已知线段为弦能画且只能画一个圆
C.以一条已知线段为弦能画且只能画两个圆
D.以一条已知线段为直径能画且只能画一个圆
答案:D
He made up his mind to devote his life ______ pollution _______ happily.
A. to prevent; to live
B. to prevent; from living
C. to preventing; to live
D. to preventing; from living
心肌梗死病理变化的描述哪项是错的
A.梗死后6小时内有肉眼可见变化
B.心肌纤维有凝固性坏死改变
C.梗死灶外周有充血、出血带
D.心肌细胞有空泡变
E.边缘出现肉芽组织