A. 受体只存在于突触后膜 B. 拮抗剂可破坏受体结构 C. 士的宁是甘氨酸受体的阻断剂 D. 哌唑嗪是心肌细胞β受体的阻断剂
A. as B. that C. where D. in which
A. for that B. for which C. for what D. of them