有价证券是指无票面金额,证明持券人有权按期取得一定收入并可自由转让和买卖的所有权或债权凭证。()
A. 正确
B. 错误
两重物质量分别为ρ1和ρ2，(假设ρ1＞ρ2)系在两条绳上；此两绳又分别围绕在半径为R1和R2的鼓轮上，鼓轮与绳的质量不计，如图所示，则鼓轮的角加速度ω为()。
New science-design technology is developed because ______.
A. this is a "designer" age
B. good idea of design will attract and maintain consumers
C. design has become an essential part of the manufacturing and selling processes
D. design is at the cutting edge of competition
对其家庭成员筛查，重要的实验室检查为
A. 血PTH测定
B. 血离子钙浓度测定
C. 皮质醇抑制试验
D. 血磷测定
E. 血TSH测定
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