Surely used in a sentence

Surely in a sentence as an adverb

"Yes, I am," said Diffie, in what surely qualified as the biggest understatement of the trial.

Then surely people, having bought it once and discovered how awesome it is, will come back again and again to pay full price.

Judging by the gossip I heard while at AOL, he surely isn't the only person using AOL's offices and food without contributing to AOL, but he's the only one who isn't actually employed by AOL.

The normalization of prison rape—like eighteenth-century japery about watching men struggle as they die on the gallows—will surely strike our descendants as chillingly sadistic, incomprehensible on the part of people who thought themselves civilized.