Why does the Leaning Tower of Pisa in Italy lean? It leans because of a mistake. It has leaned almost since the day the builders b____ it.
In 1774, the people of Pisa in Italy wanted to build a bell tower. They wanted the tower to be the m____beautiful bell tower in Italy. The city needed a bell tower because the church(教堂) did not have o____ . As soon as the first floor of the building was finished, the tower started to lean. Builders t____  to make the building straight again as they added more floors, but the leaning tower got w____ as the tower grew. It took about 180 years to finish the tower. Today, the leaning tower has eight f____  It is 54.5 meters t____. And it leans almost 4 meters to one s____ . The tower is also sinking(下沉) into the g ____ on which it was built. Every year, the tower leans a____ 1.7 cm.

读课文《我的母亲》“那一家六口终于又团聚了”一句中，“终于”的表达作用是什么？