“春种一粒粟,秋收万颗籽。”据考古发现,使用磨制石器,种植粟的是( )
A:北京人
B:山顶洞人
C:河姆渡居民
D:半坡居民
— He has few friends to share his joy and sadness, _____ he?
— _________. It’s really bad for him to keep quiet all the time.
呼吸道不仅能保证气体顺畅通过,还能对吸入的气体进行处理.下列对呼吸道结构和功能的叙述,错误的是( )