Sentence:  Thus in Mary wrote an account of the trip first strong stress on Mary marks Mary as the first in a series of people who wrote accounts of the trip , strong stress on wrote marks the writing as the first of a series of actions of Mary 's concerned with an account of her trip ( about which she may later have made speeches , for example ) , and strong stress on trip makes the trip the first of a <WSD>series</WSD> of subjects about which Mary wrote accounts . 
Meaning of the word marked with <WSD> tags:  similar things placed in order or happening one after another