注水泥质量要求阻流环距套管鞋长度应大于（）m。 10。 20。 30。 40。
A crankshaft whose center of gravity coincides with its center line is said to be （）. dynamically balanced。 statically balanced。 counter balanced。 resonantly balanced。
白盒测试与黑盒测试最主要的区别是什么？（） 白盒测试侧重于程序结构，黑盒测试侧重于功能。 白盒测试可以使用测试工具，黑盒测试不能使用工具。 白盒测试需要程序员参与，黑盒测试不需要。 黑盒测试比白盒测试应用更广泛。
How do you determine the weight of the vessel that is supported by the ground when a vessel has run aground?（）. This requires extensive calculation and is usually performed only by a naval architect not by a ship's officer。 Determine the point where aground and the draft at that point，then calculate it using the grounding formula。 Use the hydrostatic tables and enter with the mean draft before grounding and the mean draft after grounding。 Use the inclining experiment formula and substitute the change of trim for the angle of list。
简述怎样手动调节集气管压力？
在Excel 2003中，关于分类汇总的说法，以下正确的是（）。
