下面哪个是椎管内肿瘤所引起的疼痛特征性表现（）
A.针刺样疼痛
B.烧灼样疼痛
C.夜间疼痛
D.间歇性疼痛
E.偏身疼痛
参考答案：C
_____ it is rainy today, _____ he still works outside. [ ]
A. Although; but
B. But; although
C. /; although
D. Although; /
神经胚期中胚层可分化为哪几个区域？
