如图为人体体液物质交换示意图，其中正确的叙述是

①A、B、C依次为淋巴、血浆、组织液 ②乙酰胆碱可以存在于B中 ③D中的蛋白质含量相对较高 ④正常情况下，蛋白质水解酶不会存在于A中

B．②④

C．①②③

D．②③④

During the examination we are required to stay in our seats, keep our eyes on our work,      to anyone.

A．instead of speaking

B．rather than speak

C．and not to speak

D．but would not speak