USE OF ENGLISH In your notebook, complete the text with the appropriate form of the words in the box. There are two extra words. affect depend economy interest like migration sense sure Many species of bird ¹ twice a year often travelling long distances, especially if their natural habitat suffers harsh winters. Scientists are 2 ? in finding out how they navigate on these journeys. They know that birds are | Focus 4. Second Edition. Student's Book | 7/109