下列属于碱性腐蚀品的是（）。
A、葱
B、乙酰氯
C、二环乙胺
D、木馏油
参考答案：C
_____ a written permission, he had to write another letter to the president of the university. [ ]
A. Not giving
B. Not having been given
C. Having not given
D. Having not been given
中枢性瘫痪肌张力下降。（）
