The theory of falling dominoes comes from the word "dominoes"which (is, are) a game played with a set of dominoes. 2.The dominoes (is, are) laid face downwards. 3. The Alps (covers, cover) an area of 200,000 square kilometres and (is, are) the greatest mountain range in Europe. 4. Measles (is, are) an infectious disease. 5. The play was well written, but the dramatics of the performance (was, were) second-rate.