计算2x•(-3xy)2•(-x2y)3的结果是______.
2x•(-3xy)2•(-x2y)3,
=2x•9x2y2•(-x6y3),
=-18x9y5.
The noise from the top floor,loud and constant,of the meeting-room_________ can be clearly heard in our classroom.
A.to decorate
B.having been decorated
C.being decorated
D.decorating
误诊率的计算公式是()
A.真阳性例数÷(真阳性例数+假阴性例数)
B.真阳性例数÷(真阳性例数+假阳性例数)
C.真阴性例数÷(真阴性例数+假阳性例数)
D.假阴性例数÷(真阳性例数+假阴性例数)
E.假阳性例数÷(真阴性例数+假阳性例数)