听力原文： When you choose a freezer, remember it's probably going to be with you for a long time. No single style. or size is best, so it's important to know which freezer is right for your needs. First, decide if you want an upright or chest model. Uprights are more convenient. Their storage space is more accessible and they take up less floor area. However, chest models are more energy-efficient because less cold air escapes when they are open. If you're buying an upright, you'll have to choose between frostless or manual defrost. Chest freezers are always manual. Frostless freezers automatically defrost at preset intervals and remove the water. Manual models must be defrosted by hand every few months or whenever frost accumulates to about a quarter of an inch. To help your freezer reach a ripe old age, try to find a spot that's cool, dry, and away from drafts. Drafts and heat will raise the freezer's cabinet temperature and make it work harder to keep cool. That means wasted energy and a shortened compressor life. Dry air is important because high humidity can cause the freezer to rust outside and frost up inside. With proper care, a freezer can serve you for 15 years or more. Frostless models require less care than manual defrost freezers. The interior of a frostless unit should be washed periodically with warm water and baking soda or a mild soap, rinsed, and dried. To get the most from your freezer, check regularly to make sure it's providing a true zero degree temperature. Keep the freezer at least three-quarters full. The emptier it gets, the more energy is wasted. (30)