诱导神经管形成的结构是（）。
A.原条
B.原沟
C.原结
D.原窝
E.脊索
参考答案：B
The book can't belong to _______ because his is in his backpack. [ ]
A、he
B、him
C、his
D、he's
锅炉冷态调试工作有哪些内容？
