A.較小;短弧 B.較??;長(zhǎng)弧 C.較大;短弧 D.較大;長(zhǎng)弧
A.1%~1% B.5%~10% C.10%~15% D.15%~20%
A.20~40° B.40~60° C.60~80° D.80~100°