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