He was not carrying a knife when challenged by police.
Unlike 24 h glucose level, 24 h energy expenditure was robust when challenged by breakfast skipping.
If anything, its resilience comes to the fore when challenged by change.
In retaliation, Burmese forces crossed into Bengal, withdrawing only when challenged by Bengal authorities.
When challenged by fellow Twitter users, Councillor Sharp, 58, refused to back down.
When challenged by journalists, Norwegian police argued that the reconstruction sought to achieve three outcomes.
When challenged by al-Qaeda, the army and the state itself quickly shattered.
When challenged by others, she stood her ground in a firm, non-confrontational way.
The individual dropped the weapon when challenged by security personnel and fled.
"We also observed that not all staff followed infection control procedures, even when challenged by colleagues.
When challenged by passersby we said it was part of the Keep Britain Clean campaign.
