[ابو بيشو]

Sec 3, unit 6. I know that the second conditional represents impossibility, such as: If he were tall, he'd join the basketball team. I also know that the third conditional represents impossibility or an imagined action in the past. How can I differentiate between them? For example in this sentence: Without the High Dam, many Egyptian cities ... (would flood or would have flooded)?
Sender
Maha
Position
Student

The sentence you give does not have a conditional clause in it, although we can understand that it is implied in the prepositional phrase without the High Dam. But the sentence also does not give a clear time frame. Is it talking about a past time in which flooding was prevented, or is it talking about the present? As a stand-alone sentence, both endings are grammtically correct. If the sentence appears in a paragraph that gives the time frame, you can choose the verb tense accordingly.