In this task, we ask you to write a question that asks about "event duration", based on a given sentence. The question will likely start with "How long". Your question should be answerable based on the common knowledge of how long certain events usually last. Don't create questions which have explicit mentions of answers in the text. Instead, it has to be implied from what is given. In other words, we want you to use "instinct" or "common sense". Note that the written questions are not required to have a single correct answer.

Sentence: Unlike the Portuguese, the Dutch decided to do business with the Malays of Johor, who controlled the southern half of the peninsula together with Singapore and the neighboring Riau islands.
For how long did the Dutch do business with the Malays of Johor?

Sentence: He also had orang laut pirates patrolling the seas to extort tribute from passing ships.
For how long did the pirates patrol the seas?

Sentence: This sediment has been eroded off areas of land from upstream.

How long has the sediment  erosion been occuring?

