Acoordinate is a number.
a) it could not be rewritten as a true biconditional statement.
b) it uses terminology that is not precise or accurate.
c) it is a good definition.
d) it is not written in terms that have been previously defined or are clearly understood.

The  answer is A

Step-by-step explanation:

A coordinate is a set of value that show an exact position. On graphs it is a pair of numbers: the first number shows the distance along, x-axis, and the second number shows the distance up or down, y-axis. Example (x,y)=(2,3).

It is  not bi conditional.

reduce the friction between its moving parts

step-by-step explanation:

in fact, by reducing the friction between the moving parts of the machine, it is possible to reduce the energy wasted due to this friction; therefore, more input energy is converted into useful work, and this will improve the efficiency of the machine.

step-by-step explanation:

descending order means to order the polynomials from the term with the largest exponent to the term with the smallest exponent.  

therefore, the correct answer is d.