Tobject]user: which of the following is true about viruses?
a. a virus must enter a living cell to make copies of itself.
b. no virus is harmful to the cell it infects.
c. no virus contains dna or rna.
d. a virus is a type of primitive bacteria cell.

When water freezes, it . contracts expands

Is there any species that went extinct in recent years due to natural causes (not caused by human interaction). if so, what caused it?

Cpr, or cardiopulmonary resuscitation, is a first-aid technique to save lives. it involves compressions of the patient's chest cavity. which description is the best description of the functions of chest compressions in cpr? chest compressions are done to pump the heart. chest compressions are done to strengthen the rib bones. chest compressions increase carbon dioxide inhalation. chest compressions allow the patient's muscles to wake up.