A:甲×乙
B:甲×乙得F1再自交
C:甲、乙分别测交
D:甲×甲,乙×乙
____ He's my brother.
____ Who's that boy?
____ Yes, she is.
____ Is she your mother?
____ No, he isn't. He's my teacher.
____ Is he your father?
无数成功者的经历都表明自强对于人生的重要意义,而自强的关键是( )
特洛伊宝藏被发现于( )
19前面一个数是____ ,后面一个数是____ 。