経済, けいざい
1. economy, economics
2. finance, (one's) finances, financial circumstances
3. being economical, thrift
アメリカはサービス経済の国だ。
は
Particle, pronounced わ in modern Japanese
1. indicates sentence topic
2. indicates contrast with another option (stated or unstated)
3. adds emphasis
どんどん, ドンドン
Adverb, Adverb taking the 'to' particle, Onomatopoeic or mimetic word
1. drumming (noise), beating, pounding, banging, booming, stamping
2. rapidly, quickly, steadily
3. continuously, one after the other, in succession
だれかがドアをどんどんたたいている。