Пожалуйста помогите с упражнением 2.3 заранее спасибо!

2.3 1) was 2) had 3) was walking 4) noticed 5) realized 6) had met 7) had just missed 8) knew 9) recognize 10) told 11) were studying 12) am 13) do you do 14) work 15) have been living 16) don't believe 17) have been 18) have never seen 19) agreed 20) were looking