Which nutrient in excessive amounts can cause mottled tooth enamel

Could someone me? it's about drink looking at the effects and consequences of illegal drinking, what advice would you give an 11-year-old brother or sister? list at least three effects/consequences, and be specific by using examples.

Why would a smoker tend to inhale more deeply and smoke more cigarettes when he or she switches to low nicotine cigarettes

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.