甲硫氨酸的R基是—CH2—CH2—S—CH3,它的分子式是 ( )
A:C5H11O2NS
B:C3H7S
C:C4H11O2S
D:C5H10O2N
Read the text __________ and then answer the questions.
下列各项人类活动中,能持久促进能量流向更有利于人类的是( )