关于JavaScript代码的下列叙述，正确的是（）
A.A
B.B
C.C
D.D
参考答案：B
There ________ some eggs on the plate. But there ________ any bread on it.[ ]
A. are; aren't
B. are; isn't
C. is; isn't
兴奋β受体，升高cAMP水平，加强心肌收缩力的非苷类是( )。
A．地高辛B．洋地黄毒苷C．维司力农D．多巴酚丁胺E．毒毛花苷K
