以下关于胆碱能受体的说法正确的是?
A. M受体主要分布在所有自主神经节后神经元上
B. N2受体分布于神经-肌肉接头的终板膜上
C. M受体可被筒箭毒碱拮抗
D. N受体可被阿托品拮抗
中枢神经系统儿茶酚胺类递质失活的最主要方式:
A. 稀释到引起突触后反应的阈下值浓度
B. 重摄取
C. 单胺氧化酶(MAO)降解
D. 儿茶酚胺-氧化-甲基转移酶降解
For years, doctors_______millions of patients 'lives.
A. have saved
B. are saving
C. will save
D. were saving
Allen is looking forward to ______the trade fair.
A. meet
B. meeting
C. be meeting
D. having met