We will first ascertain the cause of the disaster.

I am going to ascertain the truth of the matter.

Ascertain whether they are safe or not.

It's difficult to ascertain the meaning of a hapax legomenon.

As I heard the story secondhand, I can't ascertain the truth of it.

The prince’s official London residence, Clarence House, issued a statement saying it was impossible to ascertain where he caught the virus, owing to the high number of engagements he carried out in his public role during recent weeks.

We ascertained that the people of Vileika are known for their hospitality for a good reason.

He had entertained hopes of being admitted to a sight of the young ladies, of whose beauty he had heard much; but he saw only the father. The ladies were somewhat more fortunate, for they had the advantage of ascertaining from an upper window that he wore a blue coat, and rode a black horse.

In 1778, it was calculated to be about ten millions; and, by an enumeration made in 1787, the population was ascertained to be 10,409,879; and Boetticher, in his Statistical Accounts, states the population at 11 millions.

The department of Legal Medicine Research is trying to ascertain the cause of today's conflagration.