There's no need to examine him," said the doctor. "You should know withoutasking questions. He hurt his right knee. Didn't you ___23___ the way he walked? He hurt it by burning. You see his trouser leg is burnt at the knee. It is Monday morning now. Yesterday was fine, but on Saturday the roads were wet and muddy (泥泞的). The man's trousers are muddy all over. The man ___24___ onSaturday night.