1. Although it was raining heavily, he went out without a raincoat. -> In spite of... -> Despite... -> .... However, ...

`1.` Although it was raining heavily, he went out without a raincoat.

`=>` In spite of the heavy rain, he went out without a raincoat. (In spite of + 1 cụm từ/cụm danh từ/V-ing: Mặc dù...).

`=>` Despite the heavy rain, he went out without a raincoat. (In spite of = Despite; Despite + 1 cụm từ/cụm danh từ/V-ing: Mặc dù...).

`=>` It was raining heavily. However, he went out without a raincoat. (However + 1 mệnh đề: Tuy nhiên...).