下列哪种外阴疾病容易发生恶变（）
A.纤维瘤
B.汗腺瘤
C.黑痣
D.脂肪瘤
E.平滑肌瘤
参考答案：C
Chinese is the language spoken by the ______ number of people in the world, but it`s not as _____ as English. [ ]
A. largest; widely spoken
B. large; wide spoken
C. larger; sidely speaking
D. largest; wide speaking
机车乘务员的日常业余技术学习，每月不少于（），每次不少于2h。
A、2次
B、3次
C、4次
D、5次
