黑热病的主要传染途径是（）
A.经口腔黏膜侵入传播
B.白蛉叮咬传播
C.血液传播
D.胎盘传播
E.经破损皮肤侵入传播
参考答案：B
He was _____ tired _______ he fell asleep as soon as he lay down. [ ]
A. so; that
B. too; to
C. enough; to
D. such; that
反应器床层温度偏高应怎样调节？
