выпишите предложение в котором глагол сказуемое обозначает действие в прошедшем неопределенном времени
1.1 ecological catastrophes do a lot harm to Nature, but they are much more dangerous for man  
2.2 ecological catastrophes did a lot harm to Nature, but they are much more dangerous for man
3.3 ecological catastrophes will a lot harm to Nature, but they are much more dangerous for man

4.1 a production operator checks and operates production equipment                                   5.2  a production operator check and operate production equipment                                
6.3  a production operator checked and  operated production equipment    
  

2.2 ecological catastrophes did a lot harm to Nature, 6.3  a production operator checked and  operated production equipment