sentences:  Some words, primarily short function words but also some modal verbs such as "can", have weak and strong forms depending on whether they occur in stressed or non-stressed position within a sentence.Stress in English is phonemic, and some pairs of words are distinguished by stress.For instance, the word "contract" is stressed on the first syllable ( ) when used as a noun, but on the last syllable ( ) for most meanings (for example, "reduce in size") when used as a verb.