看图填空。

阅读下面短文, 从短文后各题所给的四个选项(A、B、C、D)中, 选出可以填入空白处的最佳选项。
    Many people enjoy taking trips by themselves. Unluckily, they do not always have the best1.Instead, people should consider group tours. Taking a group tour is a wise choice for people to2themselves.
    First, group tours plan travelers' routes, so people don't have to3where they are going next or how they are getting there. They can just4and enjoy their trip.5, my family once took a group tour to China. The travel agency (旅行社)6everything for us. We just looked at the schedule the travel agency had7and followed it. Thanks to the travel agency, we had a 8trip. This made things 9on my father since he didn't have to worry about where we would go next and 10at night．
    Another11of group tours is that they allow people to communicate with one another while traveling．Travelers are able to develop12with people they would never have met13they are traveling together for a number of days. As I know, my parents 14Russia on a group tour for their honeymoon(蜜月). They15another couple on that trip, and everyone had a great time together. Even after many years, they still16together from time to time. If my parents had traveled by themselves, it would have been17for them to get to know this couple.
    In short，there is 18better than a group tour when traveling. Group tours schedule everything on the trip, and they give us the19to meet others and make friends with them. Group tours are the 20way to travel when taking a trip．

计算图形中阴影部分的面积．(单位：厘米)

实验探究题：具有活性的植物细胞在一定条件下可发生质壁分离和复原现象．质壁分离是指植物细胞因水分从液泡中流失，发生的细胞膜以内部分与细胞壁逐渐分离的现象；复原是指细胞恢复成原来的状态．

为比较相同浓度的不同溶液引起植物细胞质壁分离的效果，生物兴趣小组设计了以下实验：

操作步骤	30%的蔗糖溶液	30%的葡萄糖溶液	30%的氯化钠溶液	30%的硝酸钾溶液
制作临时装片	制作紫色洋葱鳞片叶外表皮细胞的临时装片
观察质壁分离现象，记妹质壁分离的起止时间	在盖玻片的一侧滴一滴溶液，用吸水纸在另一侧吸引，这样重复几次
	60秒	65秒	25秒	57秒
观察复原现象	在载玻片的一侧滴一滴清水，用吸水纸在另一侧吸引，？
	能	能	不能	能

请回答：

茶是我国的传统饮料。绿茶和红茶的颜色、味道差异很大，但都取自茶树。茶树的叶子里含有大量的儿茶素和咖啡因。采摘后的茶叶经揉捻、切碎后，通过“发酵”使儿茶素变成茶黄素或茶红素，即为红茶；采摘后马上加以高温翻炒，没有经过“发酵”，即为绿茶。