What is the best way to prevent atelectasis?

Dead space like ventilation may occur in the case of A: pulmonary embolism B: atelectasis C: consolidation of lung D: pleural effusion E: bronchiectasis

Which of the following diaphragm images is abnormal? A: Turtle sign B: The atelectasis is smooth and wavy. C: Adult, the right diaphragmatic top is often slightly higher than the left diaphragm. D: The anterior costophrenic angle is higher than the posterior one.