Butyrate can function as ： A: protein methylation B: Protein acetylation C: Protein phosphorylation D: Protein deacetylation

The phase 2 reactions of biotransformation include A: conjugation reaction with Gly B: conjugation reaction with glutathione C: acetylation D: methylation E: conjugation reaction with sulfate

The bioavailability of L-dopa is very low, this is due to A: difficulty to pass through the brain barrier B: rapid acetylation in liver C: peripheral hydroxylation D: a low absorption rate E: rapid peripheral decarboxylation