水平传播(horizontaltransmission)
参考答案:
病毒在人群不同个体间进行的传播,其导致的感染称为水平感染.其常见途径有:呼吸道,消化道,皮肤,粘膜,输血等.
The old building which ______ the 5th century is going to be rebuilt.
A.dating from
B.dates from
C.dated from
D.dating back to
如图所示的电路中,当P从a端滑到b端时,灯泡的亮度、电压表V1以及电压表V2的示数变化情况是:
A、灯泡变亮,V1变大,V2变小
B、灯泡变暗,V1变大,V2变小
C、灯泡变暗,V1变小,V2变小
D、灯泡亮度不变,V1变大,V2不变