结构中不含有吡啶环钙通道阻滞剂（）
A．洛伐他汀
B．多巴酚丁胺
C．硝苯地平
D．维拉帕米
E．利血平
参考答案：D
Most people think that English is _____ useful language, but some students think it's _____ unimportant subject. [ ]
A. a, an
B. a, an
C. an, an
D. an, a
可诱导调节(inducible regulation)
