-ing form as a subject of the sentence

[126]

I've done some exercises, but I'm not sure that my solutions are correct. There are some examples from one of the exercises (my solutions are in violet):

Use the cues to write sentences.
do exams/stressful
Doing exams is stressful.
swim in the sea/in the UK/not always enjoyable
Swimming in the sea in the UK isn't always enjoyable.

[lucalita009]

They are correct.

[David L.]

I think so too.