光纤是由()和包层组成。
参考答案:纤芯
Many people who were once _____ now get better jobs after further education. [ ]
A. out of trouble
B. in need
C. out of work
D. in question
处于市场领导地位的企业实施的办法有保持特色,扩大企业之间的距离,树立良好、独特的企业形象。( )