Pres. perf. simple vs pres. perf. contin.

1. Pres . Perf . Simple  ( HAVE/HAS + PARTICIPLE ) Pres . Perf . Continuous  ( HAVE/HAS + BEEN + V- ing ) Both the  Pres. Perf . Simple   and the  Pres. Perf . Continuous   are used to express that an action began in the past and is still going on or has just finished.  But there is often a difference in meaning:  We use the  Pres. Perf . Simple  mainly to express that an action is completed or to emphasise the result ( what / how much / how often ): I   have written  5 letters. = (t he letters are already written ) I   have been  to London twice. = ( now I´m at home ) We use the  Pres. Perf . Continuous  to emphasise the duration or continuous course of an action ( how long ): I   have been writing  for an hour. = ( up until now ) I   have been doing  my homework. = ( up until now )

2. PRES. PERF. SIMPLE Ever Never Already Just Still Yet Recently PRES. PERF. CONTINUOUS All ( day , week , …) For Since This week , year , …