Randomized, double-blind and placebo-controlled study to evaluate the safety, tolerability, and pharmacokinetic characteristics of SYH2059 powder for inhalation after single and multiple doses in healthy subjects. The study is composed of 2 parts. Part 1 is to assess the safety, tolerability and pharmacokinetics of a single ascending dose of SYH2059 powder for inhalation. Part 2 is to assess the safety, tolerability and pharmacokinetics of a multiple ascending dose of SYH2059 powder for inhalation.