Betty is buying some butter now. Present Continuous Betty often buys butter. Present Simple Betty has already bought butter. Present Perfect Betty has been buying some butter for 5 minutes. Present Perfect Continuous Betty bought some butter yesterday. Past Simple Betty was buying some butter when I saw her. Past Continuous Betty had bought some butter by 5 o' clock. Past Perfect Betty had been buying some butter for 5 minutes by that moment. Past Perfect Continuous Betty will buy some butter tomorrow, I'm sure. Future Simple Betty wil be buying some butter at that moment. Future Continuous Betty will have bought some butter by that time. Future Perfect Betty will have been buying some butter for 5 minutes by the time you come. Future Perfect Continuous
Betty often buys butter. Present Simple
Betty has already bought butter. Present Perfect
Betty has been buying some butter for 5 minutes. Present Perfect Continuous
Betty bought some butter yesterday. Past Simple
Betty was buying some butter when I saw her. Past Continuous
Betty had bought some butter by 5 o' clock. Past Perfect
Betty had been buying some butter for 5 minutes by that moment. Past Perfect Continuous
Betty will buy some butter tomorrow, I'm sure. Future Simple
Betty wil be buying some butter at that moment. Future Continuous
Betty will have bought some butter by that time. Future Perfect
Betty will have been buying some butter for 5 minutes by the time you come. Future Perfect Continuous