实验过程中应仔细观察实验现象并及时做好实验记录,原始记录要完整、真实、准确、清楚。
参考答案:对
30. Had it not been for the fact that I _____ absent, I would have asked you to do this right now.
A.had been
B.were
C.should be
D.Was
就管流而言,对液体的流型转变无影响的因素是()。
A、液体几何尺寸
B、液体的平均速度
C、液体的密度和粘度
D、液体的表面张力和普兰转数