This study is a randomized, active- and placebo-controlled, single-dose, seven-arm, crossover and dose-ranging design. This study aims to evaluate the efficacy and initial safety profiles, and to identify the optimum dose of A006, from a select dose-range for future clinical PK/PD and Phase III studies. This study is to be conducted in generally healthy, adult subjects who have mild-to-moderate persistent asthma for at least 6 months prior to Screening.