21．以下有關(guān)丹參的描述正確的是(      )

A．丹參能收縮冠脈                                    B.丹參對冠脈的作用不確定

C.丹參能擴(kuò)張冠脈                                      D.以上均不是

22．下列藥物中具有鎮(zhèn)靜作用的是(      )

A．丹參                                                     B.莪術(shù)

C.益母草                                                    D.川芎

23．可治療白細(xì)胞減少的藥物是(      )

A．川芎                                                     B.丹參

C.延胡索                                                    D.益母草

24．川芎中可解除血管平滑肌痙攣的成分是(      )

A．川芎嗪                                                  B.揮發(fā)油

C.川芎總堿                                                 D.丁烯苯肽

25．益母草興奮子宮的有效成分是(      )

A．益母草堿                                              B.維生素A

C.黃酮類物質(zhì)                                             D.亞麻酸