当時は彼は若くたくましく精力的だった。

当時は彼は若くたくましく精力的だった。

In those days, he was still strong and energetic.

当時(とうじ)は彼(かれ)は若(わか)くたくましく精力的(せいりょくてき)だった。

Tōji wa kare wa wakaku takumashiku seiryokuteki datta.

当時 (とうじ)

at that time; in those days

は (は)

topic marker particle; indicates contrast with another option (stated or unstated); adds emphasis

彼 (かれ)

he; him; his; boyfriend

若い (わかい)

young; youthful; immature; green; low (number); small

逞しい (たくましい)

burly; strong; sturdy; indomitable; indefatigable; strong-willed; resolute; bold; robust (vitality, appetite, economic growth, etc.); strong

精力的 (せいりょくてき)

energetic; vigorous

だ (だ)

be; is; indicates past or completed action; indicates light imperative

Readings: トウ、あ.たる、あ.たり、あ.てる、あ.て、まさ.に、まさ.にべし

Meanings: hit, right, appropriate, himself

Readings: ジ、とき、 -どき

Meanings: time, hour

Readings: ヒ、かれ、かの、か.の

Meanings: he, that, the

Readings: ジャク、ニャク、ニャ、わか.い、わか-、も.しくわ、も.し、も.しくは、ごと.し

Meanings: young, if, perhaps, possibly, low number, immature

Readings: セイ、ショウ、シヤウ

Meanings: refined, ghost, fairy, energy, vitality, semen, excellence, purity, skill

Readings: リョク、リキ、リイ、ちから

Meanings: power, strength, strong, strain, bear up, exert

Readings: テキ、まと

Meanings: bull's eye, mark, target, object, adjective ending