A T-square is a drawing tool. It is a long straight ruler with a short piece fixed across one end, so the whole thing looks like a capital T.

A T-square is是 a drawing tool一種畫圖的工具。 It is它是 a long straight ruler一支長長的直尺， with a short piece fixed across one end一端橫著固定一小段， so所以 the whole thing整個看起來 looks like a capital T像大寫的 T。

You hook the short crosspiece over the left edge of your drawing board, and then the long arm lies flat across the paper at a perfect right angle to that edge. Slide it up or down, and every line you draw is exactly parallel to the last one. That is the whole point: it is not for measuring, it is for keeping lines straight and square when a hand alone would wobble.

You你 the short crosspiece把短的橫頭 hook over勾在 the left edge of your drawing board畫板的左邊緣上， and then然後 the long arm長的那一臂 lies flat across the paper就平平地橫在紙上， at a perfect right angle to that edge和那個邊緣剛好成直角。 Slide it up or down把它往上或往下滑， every line you draw你畫的每一條線 to the last one就和上一條 is exactly parallel完全平行。 That is the whole point這就是它全部的用意： it is not for measuring它不是拿來量的， it is for是為了 when a hand alone would wobble在只靠手會抖的時候 keeping lines straight and square讓線保持又直又方正。

Architects, engineers and design students used them constantly before computers, together with a set square (a triangle) laid on top of the T-square to get vertical and slanted lines. Today the word feels a little old-fashioned in daily work — most plans are drawn on a computer — but it is still standard in art rooms, technical drawing classes, and anywhere people draw by hand.

before computers在電腦出現以前， Architects, engineers and design students建築師、工程師和設計系學生 used them constantly整天在用， together with再配上 a set square (a triangle)一把三角板 laid on top of the T-square疊在丁字尺上， to get vertical and slanted lines來畫垂直線和斜線。 Today現在 in daily work在日常工作裡 the word feels a little old-fashioned這個字感覺有點過時了—— most plans大多數圖 are drawn on a computer都是在電腦上畫的—— but但 in art rooms, technical drawing classes在美術教室、製圖課， and anywhere people draw by hand和任何還用手畫圖的地方 it is still standard它仍然是標準用語。

It is a countable noun: one T-square, two T-squares. The capital T is kept in the spelling, and the hyphen is normal.

It is a countable noun它是可數名詞： one T-square一支丁字尺、 two T-squares兩支丁字尺。 The capital T大寫的 T is kept in the spelling在拼寫裡要保留， and the hyphen is normal連字號也是正常寫法。

You may also see the shape used loosely in other places (a 'T-square' pattern of streets, for example), but that is a stretch from the tool. Note that it is a whole object with a name, not two words 'T' and 'square' put together for the moment.

You may also see你也可能看到 the shape這個形狀 used loosely in other places被鬆鬆地用在別的地方（ a 'T-square' pattern of streets, for example例如街道排成「丁字」的樣子）， but that但那 is a stretch from the tool是從這個工具引申出去的。 Note that注意 it is它是 a whole object with a name一個有自己名字的完整物件， not不是 two words 'T' and 'square'「T」和「square」兩個字 put together for the moment臨時湊在一起。