54×(1+19),
=54×109,
=60(棵);
答:六年级同学栽了60棵.
What _____ Kathy fell and hurt her knee? [ ]
A. weather
B. whether
C. through
D. if
以下关于肺动脉高压的分级,不正确的是()
A.轻度20~35mmHg
B.轻度15~25mmHg
C.中度36~45mmHg
D.重度>45mmHg
E.重度肺动脉收缩压与体动脉收缩压比值大于0.80