渗透剂在毛细管中试验时,管内渗透剂的表面呈现为()形状
着色渗透探伤时,缺陷是以()来显示的,但应在()照射下观察
Flexible hose under pressure in a hydraulic system will ().
A. tend to twist about its long axis
B. expand in length and in diameter
C. contract in length and expand in diameter
D. flex at right angles to the applied pressure
红毛茶烘干的目的是利用高温迅速蒸发水分,并加速酶的活性,进一步促进发酵。
A. 正确
B. 错误