In English there are three degrees of word stress: stressed syllables (primary stress), half-stressed syllables (secondary stress) and weak or unstressed syllables. A large group of polysyllabic simple words bear both the primary and the secondary stresses, eg ,conver'sation.
In Russian there are only two degrees of word stress, stressed and unstressed syllables. That is why Russian learners of English must be particularly careful not to omit secondary stress in English words since the interference of Russian pronunciation habits is very strong in this case, cf
организация — .organisation, демонстрация — .demonstration, национализация — .nationalization
There are several large groups of words in English with twd equally strong stresses. These words consist of two morphemes. The use of the second strong stress is caused by the semantic significance of both equally stressed elements of the word, eg rewrite, 'foufteen.