An appropriate title for the text is most likely to be__________.
[A]Fors and Againsts of DNA testing
[B] DNA testing and It’s problems
[C]DNA testing outside the lab
[D] lies behind DNA testing
质点沿x轴运动,运动方程为x=2t2+6(SI),则质点的加速度大小为()
A. 2m/s2 B.4m/s2 C.6m/s2 D.8m/s2
假设月亮绕地球作半径为R的匀速率圆周运动,则月亮的运动周期正比于()
A. R1/2 B.R C.R3/2 D.R2
与传统的沥青防水卷材相比,氯化聚乙烯防水卷材的主要特点有哪些?最适宜用于哪些防水工程?