A.
mso-bidi-theme-font:minor-bidi;mso-ansi-language:EN-US;mso-fareast-language: ZH-CN;mso-bidi-language:AR-SA" xml:lang="EN-US">θA=θB=0
B.
mso-bidi-theme-font:minor-bidi;mso-ansi-language:EN-US;mso-fareast-language: ZH-CN;mso-bidi-language:AR-SA">θ A=0 ,θ B= θ max
C.
mso-bidi-theme-font:minor-bidi;mso-ansi-language:EN-US;mso-fareast-language: ZH-CN;mso-bidi-language:AR-SA">从 A 到 B 各截面的转角均相等
D.
mso-bidi-theme-font:minor-bidi;mso-ansi-language:EN-US;mso-fareast-language: ZH-CN;mso-bidi-language:AR-SA" xml:lang="EN-US">θA=θB= m/L