来源：环球雅思网　www.ielts.com.cn 2006-3-22

conventional
traditional, historical, past; accepted, common, regular, routine, mainstream, ordinary

early
first, old, ancient, primitive, previous, former, remote

simulate
virtual, create, reproduce, pretend, imitate

artificial
synthetic, fabricated, contrived, fake, mock, bogus, counterfeit, pseudo

reduce
curtail, cut, decrease, halve, impair, lessen, moderate, trim, slash

future
what's next, prospect, approaching, expected, destined, forthcoming

worldwide
international, cosmopolitan, global, universal, ubiquitous, widespread, around the world

develop
evolve, advance, grow, improve, progress, flourish

find
discover, come across, encounter, hit on, expose, notice, note, observe, recognize, spot, uncover

demand
request, claim, need, order, require, call for

decline
decrease, degeneration, drop, fall, recession, depression, reduction, slump, worsening

significance
importance, milestone, impact, justification, gist, implication, point, purport, vital

prevelant
common, usual, prevailing, widespread, systematic, collective, general, popular

objection
chanllenge, complaint, disapproval, opposition, protest, query, question, remonstration

obstacle
bar, barricade, barrier, block, blockage, check, obstruction, problem, snag, hurdle

commercial
business, economic, financial, mercantile, profitable, pecuniary

inevitable
unavoidable, certain, destined, fated, inescapable, sure

millitary
armed, belligerent, army, weapon, warlike

role
function (provide, support, weaken, smooth, solve), job, position, duty, post, task, contribution

recent
modern, current, now, nowadays, today, contemporaneous, new, novel, present, up-to-date

difficulty
handicap, hardship, adversity, challenge, complication, dilemma, perplexity, plight, trouble

how
describe, operate, explain, clarify, demonstrate, eludicate, expound, illustrate, interpret, account for