A. 皮内注射 B. 皮下注射 C. 口服 D. 吸入
A. 防尘 B. 防污 C. 防爆 D. 防腐
A. about one-quarter of the vessel's length from the stern B. at the bow C. about one-third of the vessel's length from the bow D. aft of the propeller
A. 正确 B. 错误