What refers to an object positioned in the front of somebody or something

Describe some of the common health conditions associated with air pollution.

What is the function of reverse transcriptase in retroviruses? a) it uses viral rna as a template for dna synthesis.b) it converts host cell rna into viral dna.c) it translates viral rna into proteins.d) it uses viral rna as a template for making complementary rna strands.

What is your thoughts on the use of medical marijuana? (social experiment) re posted i need 5 opinions there are no wrong answers.