关于慢性硬膜下血肿，下列哪种说法是错误的
A．可有精神症状B．可有肢体偏瘫C．一定有外伤史D．多见于中老年E．可有颅内压增高症状
参考答案：C
With some technical problems to be solved, it may be a while _____ the system is put into use. [ ]
A. when
B. after
C. since
D. before
饼干的分类、基本工艺流程；韧性饼干生产工艺与酥性饼干生产工艺之比较
