设某圆曲线偏角ɑ=20°,R=120m,则主点测设元素为: T=（)A.21.2mB.22.2mC.23.2mD.24.2mE=（)A.1.6mB

设某圆曲线偏角ɑ=20°,R=120m,则主点测设元素为: T=()A.21.2m

B.22.2m

C.23.2m

D.24.2m

E=()A.1.6m

B.1.7m

C.1.8m

D.1.9m

D=()A.0.3m

B.0.5m

C.0.7m

D.0.9m

L=()A.40.9m

B.41.9m

C.42.9m

D.43.9m

请帮忙给出每个问题的正确答案和分析，谢谢！