冬季留针时间是：
A．1～2天B．2～3天C．2～5天D．3～5天E．3～7天
参考答案：E
已知天冬酰胺的R基为（-C2H4ON），现有一分子式为C63H103N17S2的多肽，其中含有2个天冬酰胺。上述多肽中最多有肽键 ( )
A．17个
B．16个
C．15个
D．14个
When _____, the wholesale vegetable market will be the largest one in China. [ ]
A. completed
B. completing
C. to be completed
D. being completed
