During the 20th century the Swedish language underwent many changes. These changes happened in different aspects of the language such as orthography, pronunciation, morphology, and syntax. The main causes for the changes were urbanisation, industrialisation, compulsory education, the development of the standard language and the influence of mass media. The written and the spoken language became more similar to each other, with fewer differences. The spelling reform of 1906 standardized the orthography while sentences became shorter and simpler. In the first half of the century plural verb forms gradually disappeared from the language. Many new words entered the language, especially from English. The Swedish language in Finland lost its position as a main language to Finnish. For the most part the written Swedish language in Finland has developed in parallel with Swedish in Sweden while some differences in pronunciation remain. Dictionaries and vocabularies such as SAOB and SAOL where of significant importance when it came to documenting the Swedish language.