When Neville Longbottom, the boy who kept losing his toad, was called, he fell over on his way to the stool. The hat took a long time to decide with Neville.
{When|As|The moment} Neville Longbottom, the boy who {kept losing|always misplaced|continuously lost} his toad, was called, he {fell over|tripped|stumbled} on his way to the stool. The hat took {a long time|quite a while|ages} to decide with Neville.