—How many friends will come to your ________birthday? — About ________.
A:fifteen; fifteen
B:fifteenth; fifteenth
C:fifteen; fifteenth
D:fifteenth; fifteen
某22肽被水解成1个4肽,2个3肽,2个6肽,则这些短肽的氨基总数的最小值及肽键总数依次是 ( )
不同时代的口号可以解读历史。如下图中口号出现的背景是( )
唾液淀粉酶进入胃后,将( )