经纬仪在进行角度观测之前，不必要满足的条件是（    ）。

A、<span style="FONT-FAMILY: &#39;Times New Roman&#39;,&#39;serif&#39;; FONT-SIZE: 14px">LL⊥VV </span>

B、<span style="FONT-FAMILY: &#39;Times New Roman&#39;,&#39;serif&#39;; FONT-SIZE: 14px">CC⊥HH </span>

C、<span style="FONT-FAMILY: &#39;Times New Roman&#39;,&#39;serif&#39;; FONT-SIZE: 14px">HH⊥VV </span>

D、<span style="FONT-FAMILY: &#39;Times New Roman&#39;,&#39;serif&#39;; FONT-SIZE: 14px; TEXT-DECORATION: none">CC⊥L′L′</span>