When & While 何時 和 正當

Marisa was reading the map while John was driving the car.
Marisa 正在看地圖，當 John 正在開著車子。

We were having a party when the man delivered the pizza.
我們在開歡樂會時，有個男的送來了披薩。

While → Two actions together  正當 → 兩個動作同時發生
Past progressive sentence + while + Past progressive sentence
過去進行式句子 + while + 過去進行式句子
When → Iinterruption of the first action  在那時 → 中斷第一個動作
Past progressive sentence + when + simple past sentence
過去進行式句子 + when + 簡單過去式句子


Conjunction 連接詞

While = during or in the time that.

When = upon or after which; and then.

English Grammar 英文文法

Basically a conjunction connects two words, sentences or clauses together.

基本上一個連接詞連接兩個字、句子或子句，在一起。

 although, and, because, but, if, or, so, unless, when, while ...

There are two types of conjunction: coordinating conjunctions and subordinating conjunctions

有兩類的連接詞： 對等連接詞(台灣)/並列連詞(中國大陸) 和 從屬連接詞

You can also use conjunctions in pairs, these are called correlatives.

你也可以用成對的連接詞，這些叫做相關連接詞(台灣)/關聯連詞(中國大陸)。

Coordinating conjuctions include: for, and, nor, but, or, yet and so.

對等連接詞包括：for, and, nor, but, or, yet and so.

Subordinating conjuctions include: after, although, because, before, if, in case, so that, therefore, unless, when, while ...

從屬連接詞包括：after, although, because, before, if, in case, so that, therefore, unless, when, while ...

Coordinating correlatives: both ... and, either ... or, neither ... nor, not only ... but also.

相關連接詞：both ... and, either ... or, neither ... nor, not only ... but also.