Completar Frases present perfect and continuousVersión en línea Complete the text about Arctic sea ice with the verbs in brackets in the most probable tense: present perfect simple or continuous. por bernardo de santiago 1 has depended been disappearing caused has been have have has studying have have has losing become been been has become been decreasing Scientists ( study ) changes in Arctic sea ice for around 100 years . As measuring devices and satellite analysis ( become ) more accurate , it ( become ) clear that the amount of Arctic sea ice ( decrease ) steadily for several decades . In fact , the Arctic ( lose ) 75% of its summer sea ice volume over the past three decades . This is mainly due to global warming . However , the amount of ice lost each year ( depend ) not only on global warming , but on a number of other things such as local weather patterns . In some years these things ( cause ) more or less sea ice to melt . However , even though in one year there may ( be ) more sea ice than in the previous year , the trend is that Arctic summer sea ice ( disappear ) at a rate of around 2 . 5% per year .
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