广义的有价证券可分为商品证券、货币证券、资本证券和其他证券。属于资本证券的是______。
A.本票 B.股票 C.汇票 D.债券 E.支票
参考答案:B,D
酶能催化化学反应是由于
A.提供能量B.降低反应自由能变化C.降低底物的能量水平D.提高产物的能量水平E.降低反应的活化能
Communication protocols are (66) connection-oriented or connectionless, (67) whether the sender of a message needs to contact and maintain a dialog with the recipient or (68) send a message without any, prior connect and with the hope that the recipient receives everything. (69) .These methods (70) the two ways that communication is implemented on networks.
A.make known
B.disclose
C.reveal
D.discover