This is the most difficult case I have ever faced.

He got involved in a love affair.

The Tiananmen Square incident is an important event in Chinese history.

The Marco Polo Bridge Incident was the trigger for the Sino-Japanese War.

We conducted a questionnaire survey for the development of new products.

We need to conduct a factual investigation on this issue.

We went to the scene for fact-finding.

The next census will be conducted next year.

When will the next national census be conducted?

According to the latest public opinion poll, it has become clear that many people are in favor of environmental protection.