Dưới đây là đoạn văn đã được điền từ thích hợp:

Camels
Camels are one of the only large animals that can live happily in the Sahara Desert. The hot weather and strong winds are not a (19) **problem** for them. Also, they do not need to eat or drink every day, and this (20) **makes** them very useful to the people who live there.
Camels begin working at the age of about four years old and don't stop until they are around 25 to 30. They can carry people or things a very long (21) **way** and because of this they are sometimes (22) **called** the 'ships of the desert'.
These days, there are roads across some (23) **parts** of the Sahara, so buses and lorries are often (24) **used**. However, in places where there are no roads, camels are still the only type of transport.