raining/ it/ ,/ Although/ went/ we/ swimming./ was/ heavily/ → _________________________________________________________.
Giải thích
Đáp án đúng: Although it was raining heavily, we went swimming.
Although + clause, clause: mặc dù…
Dịch nghĩa: Mặc dù trời mưa rất to nhưng chúng tôi vẫn đi bơi.