B: I'm learning English with Voice of American . Their Learning English website is available 24/7!

　　A: Twenty-four/seven, wow! Maybe I should learn English online, too!

　　There are 24 hours in a day, and seven days in a week. When you say "24/7" in a conversation, it refers to 24 hours a day, 7 days a week. It is another way of saying -- all day and all night, every day of the week.

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