诊断下呼吸道感染时，经纤维支气管镜或人工气道吸引采集的下呼吸道分泌无病原菌数需（）

A.≥10³cfu/ml

B.≥10⁴cfu/ml

C.≥10⁵cfu/ml

D.≥10⁶cfu/ml

E.≥10⁷cfu/ml

With the gradual improvement of transportation and communications, farmers have now had easier ______ to cities and towns.

A．access

B．reach

C．approach

D．touch