Paul wants to buy some blank discs. Listen to his conversation with the sales assistant, and decide whether these sentences are true or f alse . Then fill the blanks with your answer (T or F) 1. A DVD is an optical digital disc that can be used for video , audio and data storage. ( ) 2. The dimensions (尺寸) of a CD and a DVD are the same: 1.3 mm thick and 13 cm in diameter (直径). ( ) 3. The data on a DVD is read with a laser beam. ( ) 4. A basic DVD can hold 3.7 gigabytes. ( ) 5. You need a hard drive to read DVDs. ( ) 6. DVD-Video discs can hold full-length movies. ( ) 7. A DVD Writer is not compatible with old CD-ROMs. ( )