高频保护发讯机的输出滤波器属于()。
A、高频滤波器
B、带通滤波器
C、低通滤波器
参考答案:B
轿厢与对重之间的间隔距离应不小于()㎜.
A.20
B.30
C.40
D.50
Prevention of preterm births is vital for which of the following reasons
A. It’s costly to care for these neonates.B. These neonates are usually mentally retarded.C. Preterm birth causes high incidence of the neonatal deaths.D. These neonates usually wind up with long-term health care needs.