the old english. it is described as the period of full inflections（词尾变化）, since during most of this period the case endings of the noun, the adjective and the conjunction（结合）of the verbs were not weakened. old english was a highly inflected language. it had a complete system（体系）of declensions（变格）with four cases and conjunctions. so old english grammar differs from modern english grammar in these aspects（方面）. the period from 1150 is known as the middle english period. it is known as the period of reducing inflections. this period was marked by important changes in the english language. the norman conquest was the cause of these changes. the change of this period had a great effect on both grammar and vocabulary. in this
