实践出真知。经多次总结爆破经验后,爆破安全警戒范围可适当减小。
参考答案:错
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