Давайте разберёмся с каждым предложением и преобразуем слова так, чтобы они грамматически соответствовали содержанию текста.
TEACH
Правильное слово: TEACHER
Предложение: He said that he TEACHER me some basic skating skills the next Saturday but disappeared for weeks.NOT/CAN
Правильное слово: COULDN'T
Предложение: At first, I wanted to give the skates to someone else but I COULDN'T think of anybody who met both requirements - to be keen on roller skating and to have the same size feet as mine.FORGET
Правильное слово: FORGOT
Предложение: So, I put the skates on the shelf in the pantry and FORGOT about them.TIDY
Правильное слово: TIDYING
Предложение: "What are these?" my mum asked. She saw the skates when she TIDYING up the pantry, "Why do you never go skating?"GO
Правильное слово: WOULD GO
Предложение: "I WOULD GO skating if I could skate. But unfortunately I can't," I said. "And it's better to learn to skate in childhood, isn't it?"YOUNG
Правильное слово: YOUNGER
Предложение: "Right," Mum nodded, "But you have no choice. You'll never be any YOUNGER than you are now."BE
Правильное слово: WERE
Предложение: That sounded like a good reason to start something new, I put the skates in my rucksack and headed to the park. There WERE lots of skaters in the park.THEY
Правильное слово: THEY (нет изменений, просто подстановка)
Предложение: Most of THEY moved gracefully and effortlessly. Some looked really clumsy.
Теперь у вас есть необходимые преобразования слов для каждого предложения. Если вам нужны дополнительные объяснения или практика, не стесняйтесь спрашивать!