20 1. find the defi nitions and match. 1) cause a) a fact which is put forward as a motive 2) reason b) that / which makes a thing happen 3) effect c) the result 2.choose the correct form of the verb. 1. the number of days in a week is/are seven. 2. a number of streets in our city is/are still known by their old names. 3. the number of workers in our group at the camp was/were six