What does not have to happen in order for a pregnancy to occur?

menstruation
implantation
fertilization
ovulation

This is the new face book like like like like like like

When the dental assistant is seated in the correct position is usually what

Which of the following supports the argument that viruses are nonliving? a) they are not cellular.b) their dna does not encode proteins.c) they have rna rather than dna.d) they do not evolve.