A.細(xì)而長(zhǎng)的圓拄型 B.扁平形 C.細(xì)而短 D.粗而長(zhǎng)
A.3° B.6° C.9° D.12°
A.脈動(dòng) B.旋轉(zhuǎn) C.恒定 D.不變