This is principally because the major export markets are slowing...这主要是因为主要出口市场发展缓慢。Embryonic development seems to be controlled principally by a very small number of master genes.胚胎发育似乎主要受制于少数主导基因。
英汉词典释义
adv.
主要地
He had married her principally for the sake of her father’s property.他所以要娶她,主要是为了她父亲的财产。Our club was composed principally of students,with an admixture of young clerks.我们的俱乐部主要由大学生组成,外加一些年轻的职员。