1) 先后次序关系：at this time; first; second; at last; next;previously; simultaneously; eventually;last but not least;to begin with;to start with;to end with;finally;seeing...;since then;first of all;afterwards; following this; preceding this.
2) 因果关系：because;because of this;being that;another important factor/reason of... ; since; as; for; in that...; owing to; due to; for the reason that...; in view of; the reason seems to be obvious; there are about... ;for this reason; as a result of this; therefore;...and so...; consequently;as a result; thus; hence; so;so that...; in consequence; as a consequence; accordingly; inevitably; under these conditions; thereupon.
