What unit is best suited for measuring the volume of a test tube?

 The correct answer is :  Milliliter

Explanation:  In the metric system the milliliter is widely used to measure small volumes. One milliliter is equivalent to a cubic centimeter. Volume is the amount of three-dimensional space enclosed within a closed surface. The large test tubes are 150 mm high and have an approximate volume of 22 ml.

an informal structure in a bureaucracy would be something like so-called "office politics". where there's a formal structure set up for the organization, but then an informal subculture as well that has a way of organizing the bureaucracy further. this can be positive because it sets up an added degree of organization, albeit informal, within the bureaucracy.