A.長(zhǎng)而速 B.長(zhǎng)而緩 C.短而緩 D.短而速
A.25%~30% B.20%~30% C.30%~35% D.35%~40%
A. B.λ2(δ2-ρ)<λ1(δ1-ρ) C. D.