Краткое пояснение: Необходимо преобразовать слова, напечатанные заглавными буквами, чтобы они грамматически соответствовали содержанию текста.
Dogs. Many experts think that around 20,000 years ago, wolves and humans started to live side by side. Over time, some wild animals became tamed. For example, wolves chased away dangerous animals. They ate food that humans threw away. (THROW - прошедшее время). Dogs became humans' friends by accident. (BECOME - прошедшее время). One of the reasons is that dogs are cleverer than other animals. (CLEVER - сравнительная степень). They can learn quickly. (LEARN - модальный глагол). Most dogs learn new behavior in just four tries. If you have a dog, think of a new trick and try to teach it to do it. Keep the instruction enjoyable for the best results. When your dog does a command, offer a small treat or say "Good dog!” (DO - выполняет действие).
Ответ: threw, became, cleverer, learn, does