`21.` didn't go

last Sunday → QKĐ (S + didn't + V_inf)

`22.` Did you find

yesterday → QKĐ (Did + S + V_inf?)

`23.` went, were studying

Hành động đang xảy ra trong quá khứ → QKTD (S + was/ were + V_ing)

Hành động chen vào → QKĐ (S + V_ed/ V2)

`24.` will be

tomorrow → TLĐ (S + will + V_inf)

`25.` were painting

Hành động đang xảy ra trong quá khứ → QKTD (S + was/ were + V_ing)

Hành động chen vào → QKĐ (S + V_ed/ V2)

`26.` will build

next year → TLĐ (S + will + V_inf)

`27.` have worked

for many years → HTHT (S + has/ have + V_ed/ V3)

`28.` were playing

at 4 o'clock yesterday → QKTD (S + was/ were + V_ing)

`29.` see

every morning → HTĐ (S + V_inf/ V_s/ V_es)

`30.` did you do

last night → QKĐ (Question word + did + S + V_inf?)

`31.` is

often → HTĐ (S + is/ am/ are + ...)

`32.` didn't buy

yesterday → QKĐ (S + V_ed/ V2)

`33.` are playing

at present → HTTD (S + is/ am/ are + V_ing)

`34.` will go

next summer → TLĐ (S + will + V_inf)

`35.` to tell

'd like (would like) + to + V_inf: muốn làm gì

`36.` to eat

S + need + to + V_inf: cần làm gì

`37.` am studying

Hành động đang diễn ra → HTTD (S + is/ am/ are + V_ing)

`38.` boils

Hành động diễn ra thường xuyên → HTĐ (S + V_inf/ V_s/ V_es)

`39.` is climbing

Look! → HTTD (S + is/ am/ are + V_ing)

`40.` haven't seen 

since last week → HTHT (S + hasn't/ haven't + V_ed/ V3)

`41.` have you known

How long + has/ have + S + V_ed/ V3?)

`42.` burned, was cooking

Hành động đang xảy ra trong quá khứ → QKTD (S + was/ were + V_ing)

Hành động chen vào → QKĐ (S + V_ed/ V2)

`43.` were crossing, shouted

Hành động đang xảy ra trong quá khứ → QKTD (S + was/ were + V_ing)

Hành động chen vào → QKĐ (S + V_ed/ V2)

`44.` did you do

yesterday → QKĐ (Question word + did + S + V_inf?)

`45.` won't rain, start

S + will + (not) + V_inf + when + S + V_inf/ V_s/ V_es