Task 4. Put the verbs in brackets in the correct non-finite form (Infinitive, to-Infinitive or -ing form). Extreme sports are not for everyone. But for people who enjoy 1) (live) life to the full, they are the only type of sports worth 2) (do)! The latest extreme sport to become popular is sandboarding. You are able 3) (lie down) or stand up. Both your feet are tied to the board to prevent you from 4) (fall off). Some sandboarders, however, feel like 5) (keep) their feet untied because it allows more freedom of movement. Lying down can be even more fun.

Решение:

• 1. Extreme sports are not for everyone. But for people who enjoy living life to the full, they are the only type of sports worth 2) (do)! (После глагола 'enjoy' используется герундий -ing).
• 2. ...they are the only type of sports worth doing! (После предлога 'worth' используется герундий -ing).
• 3. You are able to lie down or stand up. (После 'be able to' используется инфинитив с частицей 'to').
• 4. ...to prevent you from falling off. (После предлога 'from' используется герундий -ing).
• 5. Some sandboarders, however, feel like keeping their feet untied... (После глагола 'feel like' используется герундий -ing).

Ответ: 1. living, 2. doing, 3. to lie down, 4. falling off, 5. keeping