Re数较小时()起主要作用。
A、粘滞阻力
B、惯性损失
C、磨擦阻力
参考答案:A
______are! I've never seen so many beautiful flowers. [ ]
A. What beautiful the flowers
B. How beautiful the flowers
C. What beautiful flowers
D. How beautiful flowers
焊缝中的偏析主要有()偏析和()偏析两种。