单项选择题
A.5s B.10s C.15s D.20s
A.4倍 B.5倍 C.6倍 D.7倍
A.150KΩ B.200KΩ C.250KΩ D.300KΩ
A.10% B.15% C.20% D.25%
微信扫一扫,加关注免费搜题