（3.1）A支座的水平方向支座反力FAx=（  ）（2分）

<span lang、"EN-US">0</span>

<span lang、"EN-US">2kN</span><span>（</span><span lang="EN-US">←</span><span>）</span>

<span lang、"EN-US">4kN</span><span>（</span><span lang="EN-US">→</span><span>）</span>

<span lang、"EN-US">4kN</span><span>（</span><span lang="EN-US">←</span><span>）</span>