to cross one's t's (and dot one's i's) "to be exact" is attested from 1849. Phrase to a T "exactly" is recorded from 1690s, though the exact signification remains uncertain despite much speculation. The measuring tool called a T-square (sometimes suggested as the source of this) is recorded by that name only from 1785. The T-cell (1970) so called because they are derived from the thymus. As a medieval numeral, T represented 160.
例文
1. T -shirts are a nice little earner and it 's better than the dole.
T T Tシャツを売ってお金を得るのは簡単で、救済金を受け取るより良い。
2. T -shirts now seem almost de rigueur in the West End.
T Tシャツは、今ではロンドンのウエストエンドのファッションパーソンの必須アイテムとなっている。
3.He had bare feet，a T ?shirt and cords on.
彼は裸足で、 T シャツとコーデュロイのズボンを着ている。
4. T -shirts，the epitome of American casualness，have moved upscale.
アメリカのカジュアルスタイルを象徴する T Tシャツは、すでにハイエンド消費市場に進出している。
5.He wore a T -shirt that had been tie-dyed in bright colours.