Read the text and put 3 questions to it:
Rivers carry sediment down their riverbeds, allowing for the formation of depositional features such as river deltas, alluvial fans, braided rivers, oxbow lakes, levees and coastal shores. The construction of a dam blocks the flow of sediment downstream, leading to downstream erosion of these sedimentary depositional environments, and increased sediment build-up in the reservoir.
While the rate of sedimentation varies for each dam and each river, eventually all reservoirs develop a reduced water-storage capacity due to the exchange of "live storage" space for sediment. Diminished storage capacity results in decreased ability to produce hydroelectric power, reduced availability of water for irrigation, and if left unaddressed, may ultimately result in the expiration of the dam and river.
В первом предложении действительный залог, значит вс глагол DID.
Во втором предложении страдательный залог, значит вс глагол WERE (WAS)
Если в предложении есть сигнальные слова just, already, not yet, this week, this year, today, то глагол ставим в форму Present Perfect - have (has) + глагол в III форме.
НАПРИМЕР: When did he come? - Past Simple
He has just come. - Present Perfect
В первом предложении действительный залог, значит вс глагол DID.
Во втором предложении страдательный залог, значит вс глагол WERE (WAS)
Если в предложении есть сигнальные слова just, already, not yet, this week, this year, today, то глагол ставим в форму Present Perfect - have (has) + глагол в III форме.
НАПРИМЕР: When did he come? - Past Simple
He has just come. - Present Perfect