Ex4

The union issued an ultimatum: Increase wages by 5 percent, or the workers go on strike.

Ex3

The police posted a placard asking all citizens to desist from looting.

Ex2

Charley disputed my answer to problem 9 unti I showed him definite proof that I was right. 

Ex1

First I couldn`t locate my math homework; but after a while I found it in my English notebook. I must have put it there inadvertently.