为避免蔬菜和水果受到各种污染，并保护生态环境，生产中可采取的有效措施是

①采用无土栽培②使用绿肥等有机肥③使用大量化肥④使用农药防治虫害⑤采用生物防治虫害 [ ]

A．①③④

B．①②⑤

C．②③④

D．③④⑤

The Acropolis ________ in the 5th century B. C. at a high altitude above the city in honour of

Athena, the goddess of Athens.[ ]

A. constructed  

B. was constructed

C. has been constructed  

D. is being constructed