流行性脑脊髓膜炎的传播途径只有()
A.接触传播
B.空气飞沫传播
C.医源性传播
D.经食物传播
E.经水传播
参考答案:B
A sheave is a().
A.grooved wheel in a block
B.line to hold a lifeboat next to the embarkation deck
C.partial load of grain
D.seaman's knife