角位移传感器用磁铁复位后，角位移会响3声，约30s后又响1声说明已进入激活状态。（）

王某在甲地临时从事收购废品的业务，税务机关对其采取的税款征收方式应当是（）。

A.代扣代缴

B.查账征收

C.代收代缴

D.核定征收

Networks can be interconnected by different devices．In the physical layer，networks can be connected by (64) or Hubs, which just move the bits from one network to an identical net-work. One layer up we find bridgas and swiehes, which operate at data link layer. They can accept (65) , examine the MAC address, and forward the frames to a different network while doing minor protocol translation in the process. In the network layer, we have routers that can connect two netwoks. If two networks have (66) network layer, the router may be able to translate between the packet formats. In the transport layer we find transport gateway, which can interface between the two transport connections. Finally, in the application layer, application gateways translate message

(67) . As an example, gateways between Internet e-mail and X.400 e-mail must (68) the e-mail message and change various header fields.

65（）

A．frames

B．bytes

C．packages

D．cells

尿液出现烂苹果味，可能是（）。

A.泌尿系感染

B.膀胱肿瘤

C.糖尿病酮症酸中毒

D.过多饮酒

E.苯丙酮尿症

关于速度和加速度的关系，下列说法正确的是（）

A.加速度方向保持不变，速度方向也保持不变

B.加速度大小不断变小，速度大小也不断变小

C.速度变化量越大，加速度越大

D.速度变化越快，加速度越大

马克维茨的投资组合理论认为，若干种股票组成的投资组合，其收益是这些股票收益的加权平均数，其风险等于这些股票的加权平均风险，所以投资组合能降低风险。 ( )