某化学兴趣小组用甲、乙两套装置（如图所示）进行甲酸（HCOOH）与甲醇（CH₃OH）酯化反应的实验，该有机产物在医药上，常用作磺酸甲基嘧啶、磺酸甲氧嘧啶、镇咳剂美沙芬等药物的合成原料．回答以下问题：

（1）甲酸和甲醇进行反应的化学方程式是：______．

（2）乙装置中长玻璃导管c的作用是______；冷凝水应该从______进入．

（3）接收器中饱和碳酸钠溶液的作用是______；

（4）甲、乙两套装置中效果比较好的装置是______，原因：______．

The center of flotation of a vessel is（）.

A.the center of volume of the immersed portion of the vessel

B.the center of gravity of the water plane

C.that point at which all the vertical downward forces of weight are considered to be concentrated

D.that point at which all the vertical upward forces of buoyancy are considered to be concentrated