同学们听到上课铃声,陆续回到教室,这属于生物的哪种现象( )
A:遗传现象
B:生殖现象
C:对外界刺激做出反应
D:新陈代谢
— What should I do when I feel weak and tired all day?
— _______ some food like beef may be helpful.
请回答: