Why do you need to run several tests before you can identify a mineral with 100 percent certainty? A Minerals all have the same chemical structure
B Many minerals share physical properties in common
C Minerals' physical properties can change very quickly
D A mineral can only be subjected to a few tests before it degrades

b

Explanation:

either a donut or a sphere or a pancake or a flat sphere. it depends on where the vertical line is.

if the line goes through the center of the circle and is perpendicular to a diameter containing the center, then you get a flat circle.

if the line and the diameter of a the circle meet in the center of the diameter and at an angle, you get a pancake.

if the line is on the circumference of the circle and is at right angles   to the circle you get a ring.

if the line contains the diameter, you get a sphere.

the the line is parallel to the diameter and touches the circumference, you get a donut.

b. cronkite, a trusted television personality, declared that the war was unwinnable and told the american people that the government had better find a way out

even though it went against everything the news anchors typically stood for, cronkite voiced an opinion and took a stance, telling the us that there was no way they were going to win, the war was going to end in a stalemate.