When the bell rang announcing the end of class, students came out .
A. by twos and threes
B. by two and three
C. by two and three
D. by twos or threes
网友回答
(答案→)A. by twos and threes
B. by two and three
C. by two and three
D. by twos or threes
解析：可联系答.案.网客服索取。