可防止义齿殆向脱位的部分是

A. 为内胚层形成的一条纵行管道
B. 前肠头端以口咽膜封闭
C. 后肠尾端以泄殖腔膜封闭
D. 中肠的背侧与卵黄蒂相连

A. He made the first lightning rod.
B. He invented electricity.
C. He built the Empire State Building.
D. He prevented lightning from hitting cars.

A. 0.167361
B. 0.209028
C. 0.250694
D. 0.334028
E. 0.417361