Complete the sentences with the verbs in correct tense 1.When I came home, my brother ……. a comedy film. (watch)
2.I …….. today, I have so much work to do. (not/eat)
3.Amir ….. a game while Saule…… a book. (play/read)
Diana ….. never…. a birthday party before. (have)

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Since individuals typically earn their incomes from working for companies whose requirements are constantly changing, it is quite possible that at any given time not all members of a country's potential work force will be able to find an employer that needs their labor. This would be less problematic in an economy in which such individuals had unlimited access to resources such as land in order to provide for themselves, but when the ownership of the bulk of its productive capacity resides in relatively few hands, most individuals will be dependent on employment for their economic well-being. It is typical for true capitalist economies to have rates of unemployment that fluctuate between 3% and 15%. Some economists have used the term "natural rate of unemployment" to describe this phenomenon. Depressed or stagnant economies have been known to reach unemployment rates as high as 30%, while events such as military mobilization (a good example is that of World War II) have resulted in just 1-2% unemployment, a level that is often termed "full employment". Typical unemployment rates in Western economies range between 5% and 10%. Some economists consider that a certain level of unemployment is necessary for the proper functioning of capitalist economies. Equally, some politicians have claimed that the "natural rate of unemployment" highlights the inefficiency of a capitalist economy, since not all its resources – in this case human labor – are being allocated efficiently. Some libertarian economists argue that higher unemployment rates are in part the result of minimum wage laws, as well as in part the result of misguided monetary policy, and are not inevitable in a capitalist economy. They also claim that if the value of the productive capacity of a given employee is worth less to the employer than the minimum wage, that person will become unemployed, and therefore unemployment will exist whenever the legal minimum wage exceeds the true economic value of the least productive members of the labor pool. Likewise, if the amount of money a person can obtain on welfare approaches or equals what they could make by working, that person's incentive to work will be reduced. Some unemployment is voluntary, such as when a potential job is turned down because the unemployed person is seeking a better job, is voluntarily living on savings, or has a non-wage-earning role, such as in the case of a traditional homemaker. Some measures of employment disregard these categories of unemployment, counting only people who are actively seeking work and have been unable to find any.

A doctor had been sent for by the time I entered my house.
Доктора вызвали к тому времени, когда я пришёл домой.

Объяснения:

Когда в предложении времени в указании времени стоит by (означает к (к какому-то времени)), используется время Past Perfect.

Например,

I had washed the dishes by two o'clock.
Я помыл посуду к двум часам.

Если бы в предложении было не by two o'clock, а чёткое указание времени, например at two o'clock, то использовалось бы Past Simple.

Похожее правило есть в будущем времени. Если в предложении будущего времени в указании времени стоит by, то используется не Future Perfect.
The dishes will have been washed by two o'clock.
Посуда будет вымыта к двум часам.

Если бы by отсутствовало и вместо него было просто, например, at two o'clock, то использовалось бы простое будущее время — Future Simple.