根据上下文选择正确的词填空
问题描述：
根据上下文选择正确的词填空
1.I am No.( )in my class. But Helen is the( )one.(eight,eighth)
2.There are( )boys standingin a line.The( )one isn Ben.(twenty-first,twenty-one)
3.There are( )days in a week.And we know Saturday is the( )of a week(seventh,seven)
答
eight,eighth
twenty-one twenty-first
seven seventh
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