下列哪种药物可以使瞳孔缩小

A．磺胺醋酰纳

B．氯霉素

C．利明眼药水

D．阿托品

E．匹罗卡品

Both bus and tree topologies are characterized by the use of multipoint(1)．For the bus,all stations attach,through appropriate hardware(2) known as a tap,directly to a linear transmission medium, or bus. Full-duplex operation between the station and the tap allows data to be transmitted onto the bus and received from the(3).Atransmission from any station propagates the length of the medium in both directions and can be received by all other(4).At each end ofthe bus is a(5),which absorbs any signal, removing it from the bus．

空白（3）处应选择（）

A.tree

B.bus

C.star

D.ring