依据《工程测量规范 》三等水准测量使用DS3水准仪测站的视线长（）

A.75m

B.80m

C.100m

D.50m

A.100m

B.80m

C.75m

D.50m

A.2mm

B. 3mm

C. 5mm

D. 10mm

A.10m

B.6m

C.3m

D.5m

A.±40mm

B. ±20mm

C. ±12mm

D. ±6mm

《工程测量规范》规定，三等水准测量中，视线离地面的最低高度应不小于()。

A.0.1m

B.0.2m

C.0.3m

D.0.5m

A.5m

B.3m

C.1m

D.10m

A.±40根号Lmm

B.±20根号Lmm

C.±12根号Lmm

D.±6根号Lmm

A.2mm

B.3mm

C.5mm

D.10mm