6. Grammar 2: Expressing Necessity in the Past

Careful listeners to the recording in the previous task must have noticed that the presenter also talked about some necessities; in other words, what the engineers had to or did not have to do in the past to complete the project. To distinguish properly between what was necessary and unnecessary, it is vital to understand the tiny nuances in what the associated grammar structures mean. Therefore, complete the overview in this task. After that, practise this grammar point by completing this task. Finally, complete the concise report on the Seawater Greenhouse project by filling in all the gaps here.