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.

位于我国地势第二、三级阶梯分界线上，呈东北-西南走向，又是华北平原和黄土高原分界线的山脉是

下列实例不能体现细胞膜结构特点的是（　　）

①福建南安的颜氏家族在宋代立下了永远为唐代诗人韩偓守墓的誓言。颜氏家族一言九鼎，让此承诺一代一代延续，守护这一片千年历史遗存。

②近日，天津公安公交分局的便衣警察在执行反扒任务时，成功抓获两名公交扒手，现场监控视频完整记录下了扣人心弦的抓捕过程。

③藏品因存世量稀少，历来是藏家的心头之好，又因其收藏价值高，赝品颇多，而收藏者最关注的藏品真伪问题，历来争论不休，扑溯迷离。

④用功譬如掘井，一锹下去可能会遇到瓦砾，也可能会遇到岩石。但是，只要心无旁骛，倾力深挖一口井，自有清泉涌出之日。

⑤一部网络小说动辄上千万字，文字水平鱼龙混杂，价值表达未经深思，此类问题普遍存在，即便所谓“大神级”作品也不能免俗。

⑥研讨会中，专家对电视剧《思美人》发表了各自的见解，在指出部分瑕疵之外，更盛赞这是一部雅俗共赏、富有价值的优秀作品。