问题补充：
We will learn English words this year, the teacher said to the students.
A. one thousand three hundred and twenty-one
B. a thousand and three hundred twenty-one
C. one thousand three hundred twenty-one
D. a thousand three hundreds and twenty-one
答案：
(答案→)A. one thousand three hundred and twenty-one
B. a thousand and three hundred twenty-one
C. one thousand three hundred twenty-one
D. a thousand three hundreds and twenty-one
解析：句意：今年我们学了一千三百二十个单词。在英语中数字的读法是，三位三位的断开，从右向左，第一个逗号处是thousand,第二个是million,第三个是billion，十位和个位之间用连字符，百位和十位之间加and，十位是零，也要补上and。故选A。
