trustle > EngliSea > G > Grammer > Perfect
 
 Past Perfect
Pluto had been considered the ninth planet until 2006 when it was renamed a dwarf planet.
http://qindex.info/i.php?f=4139#4150
 
 Perfect Aspect
http://qindex.info/i.php?f=4139#4143
 
 Present Perfect
If the result of the past action continues now, we use present perfect.
http://qindex.info/i.php?f=4139#4140
 
 Present Perfect
Scientists say they have found evidence of a giant planet in the solar system. There have only been two true planets discovered since ancient times. Planets have been predicted before and then were not found.
http://qindex.info/i.php?f=4139#4149
 
 Present Perfect or Past Simple (Part 1)
http://qindex.info/i.php?f=4139#4141
 
 Present Perfect or Past Simple (Part 2)
http://qindex.info/i.php?f=4139#4142

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