I couldn’t go to the cinema with my friends last night because I (not/finish) my homework yet.
I couldn’t go to the cinema with my friends last night because I had not finished my homework yet.
When we ___(come) back, it was cold in the house because Alice (not / close) the windows.
When we came back, it was cold in the house because Alice had not closed the windows.
We ___ (eat) at a restaurant last night because I (not / buy) anything for dinner.
We ate at a restaurant last night because I had not bought anything for dinner.