分类：教育/科学-学习帮助
问题：单项选择29.
29. -- morning, mr wu! you're _____ today!-- yes. i think walking is good for my health.a. by bi b. by bus c. by car d. on foot
回答：d. on foot步行
早说好，武先生，今天你步行！
是的，我认为步行有利于身体健康