九十用英语怎么说

The phrase "九十" in Chinese is usually translated into English as "ninety." This is because the number 90 is a composite number, which means it cannot be expressed as the sum of two smaller numbers (i.e., it has more than one pisor other than 1 and itself). In English, we use the word "hundred" to indicate a number that is greater than or equal to 50 but less than 100, so "ninety" is used to express this range of values.