问题 选择题 给下列的算式选择正确的答案。( ) 1. thirteen plus eight equals ( ) 2. forty plus nine equals( ) 3. ten plus fifteen equals ( ) 4. forty-one plus six equalsA. forty-seven B. twenty-one C. forty-nineD. twenty-five 答案 1. B 2. C 3. D 4. A
