Question

3)Joe has already cleaned/had already cleaned the flat by the time his mother came​

Answer 1

Ответ:

Joe had already cleaned the flat by the time his mother came​. (Нужно использовать время past perfect в первой части предложения)

Answer 2

Both of these sentences are grammatically correct, but they convey slightly different meanings:

1. Joe has already cleaned the flat by the time his mother came.

   This sentence suggests that Joe completed the cleaning of the flat before his mother arrived. The emphasis here is on the fact that Joe finished cleaning before a specific point in the past (when his mother arrived).

2. Joe had already cleaned the flat by the time his mother came.

   This sentence also suggests that Joe completed the cleaning of the flat before his mother arrived. The difference here is the use of the past perfect tense ("had already cleaned"), which emphasizes the completion of the cleaning action before another past event (his mother's arrival).

Both sentences essentially convey the same sequence of events, but the second sentence places a slightly stronger emphasis on the completion of Joe's cleaning task before his mother's arrival.