Question

They have also bought a flat,какое это время ПОМОГИТЕ

Answer 1

Present Perfect Tense 
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Answer 2

The phrase "They have also bought a flat" is in the present perfect tense. This tense is used to describe an action that started in the past and has continued up to the present, or an action that was completed in the past but has relevance to the present.

In this case, the action of buying a flat was completed in the past, but it has relevance to the present. Therefore, the present perfect tense is appropriate here.