A:①④
B:①②④
C:①②③
D:全部
读经纬网图,回答问题。
组成蛋白质的氨基酸约20种,各种氨基酸之间的不同点在于( )
I____(thought/ think) it was easy to do before.
I must get up early tomorrow morning. Please wake me ________.