1 James Cook had/could/was/were a great explorer.
2 The ancient Egyptians had/could/was/were build houses of stone.
3 Sam had/could/was/were read when he had/could/was/were 5.
4 He did paint/was painting/ painted while his mother cooked/was cooking/did cook.
5 Native Americans was respecting/respected/were respecting the environment.
6 The ancient Egyptians were transporting/transported/did transport goods by boat.
7 The streets were full/narrow/crowded of people.
8 The eruption of Vesuvius buried/put/destroyed the city under ash.
9 Only boys arrived/attended/learned school.
10 The Kwakiutl Indians wore animal clothes/tribes/skins to keep warm.

Healthy Food It’s very important to choose the right food nowadays. Healthy and balanced diet is useful for every person. We depend on food as well as the cars depend on gas, for example. It’s our natural fuel, which gives our body physical strength and health. When the body is healthy, the mind will also be healthy. Different types of food contain different nutrients for our body. Some supply us with carbohydrates, some with proteins or fats, some with vitamins and minerals, etc. Many people think that fat is bad for people and they try to cut down on it. There is even a special line of products, called low-fat. The problem is that we do need some kinds of fat, but the saturated fats from animal products, like red meat, butter and cheese, can be really bad for health. Friendly fats can be found in avocados, nuts and seeds, olives and tuna fish, and in some other products. Some people cut down on too much sugar and salt, which is also a good idea. One of the healthiest types of food is fruit and vegetables. Such organic products can be only useful if they don’t contain any chemicals and additives, which has become a common phenomenon in modern supermarkets. More and more people tend to grow fruit and vegetables in their own gardens, instead of buying them. Another problem is modified food. It’s much cheaper than ordinary food, which is why people often buy it. From the other hand, modified food can lead to dangerous diseases. The food people eat depends a lot on their culture, religion, beliefs, health and other factors. However, some rules are common for everyone. They are: less fat, sugar and salt; and more water, vitamins, fresh fruit and vegetables.

Задание немного не понятное.  Возможно что-то типа этого.

Travelling about Africa he learnt a lot about African traditions.
Путешествуя по Африке, он узнал много об африканских традициях.

Утвердительное предложение с причастным оборотом.
Travelling about Africa - причастный оборот, обстоятельство времени
he - подлежащее, личное местоимение в 3 лице ед. числа
learnt - сказуемое, глагол в Past Indefinite/Past Simple
a lot- определяющее слово/местоимение
about - предлог
African - прилагательное
traditions - исчисляемое существительное во множ. числе