A book is sliding along a desktop. Because the book is in motion, you know that the forces acting on the book are ? What is the force acting against the book?

Normal force, gravity and Friction.

Explanation:

The forces acting on the book are normal formal force which act or exerts by the table on the book while on the other hand, gravity is a force that acts in the downward direction. Friction is the force that acts against the motion of the book and is responsible for lowering speed of the book that is sliding on the surface of the table. If the friction is low between the book and table then the book moves easily on the surface.

b

is correct hope this   also i learnd this in middle school

"1. it should be, it has been for about 20 years, and it's really not much different in the end than breeding animals to have particular traits. there are always concerns about genetically engineered animals/plants affecting the environment in unexpected negative ways, but i can't think of an example where the fears didn't turn out to be baseless.  

first, as you point out, it would be a great advance in pharmacology, to be able to tailor drugs and their doses to me. the pros involve better medical treatment. the cons involve privacy issues like insurance companies denying coverage to people with genetic risk factors. looking at dna markers wouldn't affect the frequency of genetic diseases, but it would allow detection of them earlier. and ok, actually i suppose that if people used this information to avoid having children with genetic diseases, some might decrease in frequency."