咽为消化系及呼吸系所共有的通道。( )
参考答案：对
There were no doctors in the poor area, ________ the medical team had to work hard.[ ]
A. so
B. though
C. unless
氨对中枢神经系统的毒性作用主要是影响()
A．脑的蛋白质代谢
B．脑的脂肪代谢
C．脑的能量代谢
D．脑的酶代谢
E．脑的血液代谢
