English grammar – 數詞

·百位數中如果十位數是0時，百位數和個位數中見的and不可省略，其他可以省略。
·基數相當於名詞，可以以複數形式出現，後面常接of。如Hundreds of students took part in the composition competition.
·基數前面有其他數詞，用作確定數目或有saveral修飾時不用複數形式。
·倍數的表現方式有很多種：
Four fours are sixteen.
Four times four is sixteen.
This room is three times as large as that room. 這房間是那房間的三倍大。
This room is three times larger than that one. 這房間比那房間大三倍。
times一般只用於三倍以上，表示兩倍的用twice或double。
·分數的讀法還可以讀作1/2 one over two.
·分數中分子大於一的時候，分母用複數形式。如2/3讀作two thirds.
·算式的表達中，減法可以讀作 減數from被減數；除法可以讀作 除數into被除數。
·表示“幾十歲”時，應該用複數形式，並在前面加上in one’s。如In 1870s, when A was already in his fifties……