42
(A)Once
(B)Because
(C)Unless
(D)Although

 42   women currently dominate the field, cheerleading was begun by men. In the 1920s women became involved in cheerleading, but it was not until 1940s that they joined in large numbers, since so many college-aged men went off to fight in World War II. In 1948, Lawrence Herkimer, the father of modern cheerleading, founded the National Cheerleaders Association and held the first cheerleading camp.

目前 42 是女性稱霸該領域，但啦啦隊是由男性開始的。在 1920 年代，女性開始參與啦啦隊，但直到 1940 年代，她們才大量加入，因為有很多大學年齡的男性參加了二戰。 1948年，現代啦啦隊之父勞倫斯·赫基默（Lawrence Herkimer）創立了全國啦啦隊協會，並舉辦了第一屆啦啦隊訓練營。

 42   women currently dominate the field, cheerleading was begun by men.

雖然...但(轉折語氣)

I’ll be out of the office until 21th May.

5月21日之前，我都不在辦公室。

We did not eat until past midnight.

直到過了午夜我們才吃東西。

英文Until 與Not until 用法與中文意思！一次搞懂 - 全民學英文