Match each tense form with the situation(s) of it use.
A) for a past activity beginning before a past event and continuing until or after it. For the event we use ‘when’ + the past simple
b)for completed actions, events and situations in the past
c)to talk about something that happened before a past event. In sentences that have ‘when’ + past simple, to show that one event happened before the other.
d)for an unfinished activity around a time in the past
1.Past Simple
2.Past Continuous
3.Past Perfect
2. In an economic sense, intensity may mean the levels of input per unit of output.
3. He had to examine the relationships between various important items in the balance sheet.
1. ферма должна быть достаточно большой, чтобы поддерживать более одной семьи.
2. В экономическом смысле, интенсивность может означать отношение вложений к единице продукции.
3. Он должен был изучить соотношения между различными основными пунктами в балансовом отчёте.