1.contradict; contradictory

The witnesses’ statements ¡¡¡¡¡¡¡¡¡¡¡¡¡¡¡¡each other and the fact remains unclear. 

The witnesses’ statements are ¡¡¡¡¡¡¡¡¡¡¡¡¡¡and the fact remains unclear. 

2.infect; infection

A single mosquito can ¡¡¡¡¡¡¡¡¡¡¡¡a large number of people. 

Which virus has caused the ¡¡¡¡¡¡¡¡¡¡¡¡is still unknown. 

3.proof; prove

Have you got any ¡¡¡¡¡¡¡¡¡¡¡¡that you are the owner of this bike? 

How can you ¡¡¡¡¡¡¡¡¡¡¡¡that you are the owner of this bike? 

4.multiple; multiply

He suffered ¡¡¡¡¡¡¡¡¡¡¡¡injuries in the accident. 

We have to ¡¡¡¡¡¡¡¡¡¡¡¡our efforts to achieve what we want. 

5.intervene; intervention

The situation calmed down when police ¡¡¡¡¡¡¡¡¡¡¡¡¡¡. 

The ¡¡¡¡¡¡¡¡¡¡¡¡¡¡of the United Nations helped solve the issue.