Jawaban:
1.) The police stopped him because he was driving too fast
2.) I've repaired the car, you can use it now
3.) Marry and David bought their house in 2006
4.) My mother had cleaned the windows when i arrived.

Penjelasan:
1.) Kalimat majemuk dengan past continuous (s + was/were + verb-ing) itu selalu dipadukan dengan kalimat past (s + verb2 + object) contoh police stopped him.
2.) Now = time adverb buat present perfect (s + have/has + verb3)
3.) In (tahun) itu pake past tense = bought (verb2 dari buy)
4.) Kalau has/have cleaned itu when I arrive. Kalau had cleaned itu when I arrived.
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