衣原体感染的传播方式主要有()
A.呼吸道传播
B.性接触传播
C.垂直传播
D.直接接触传播
E.粪-口途径传播
参考答案:A, B, C, D
We have been excavating layers of ash almost six metres thick, which suggests that they________the fire burning all winter.
A.should keep
B.might have kept
C.should have kept
D.might keep
属于结构抗力的是()。
A.梁的受弯承载力
B.作用在梁上的均布荷载
C.梁受力后的裂缝宽度
D.梁受力后的的挠度