梅尼埃病首次发病年龄以哪个年龄段为主()。
A.20~30岁
B.30~50岁
C.50~60岁
D.60~70岁
E.70岁以上
参考答案:B
—Which of the shorts do you like better?
—I'll take _______. I like them so much. They are cheap and fashionable. [ ]
A. nothing
B. none
C. all
D. both
按照标准要求,五类双绞线的线缆衰减和近端串扰的测试必须在1-100MHz范围内进行。()