Hello everyone! I'm Lucy. My parents love travelling with me. We have been in Australia____ three days. We're having a ____ time here. Australia is ____ sixth largest country in the world. There is too much to see. And it is impossible for me to tell you ____. Sydney is a beautiful city. There are both many trees ____beautiful flowers around the houses and they look really beautiful. There are also some special ____ in Australia, such as kangaroos and koalas. They are really lovely.

    During the past three days, we've visited many ____ of interest around Sydney. I'd like to spend more time here, but we will fly to ____city, Cairns, to see coral reefs(珊瑚礁) tomorrow. People say that words cannot tell the beauty of the colorful coral. Many famous cartoon films were made there. Now we are busy packing our bags. We will enjoy____ in Cairns this time tomorrow. I'm looking ____ to going there!

油菜素内酯是植物体内一种重要的激素．为探究油菜素内酯（BL）对生长素（IAA）生理作用的影响，研究人员做了如下实验．

实验一：利用不同浓度的BL和IAA处理油菜萌发的种子，观察其对主根伸长的影响，结果如图1所示：

（1）由图1可知，单独IAA处理，对主根伸长的影响是____；BL与IAA同时处理，在IAA浓度为____ nM时，BL对主根伸长的抑制作用逐渐增强；当IAA浓度继续增加时，BL对主根伸长的影响是____ 

实验二：用放射性碳标记的IAA处理主根，检测油菜素内酯对于生长素运输的影响．实验方法及结果如图2：

（2）图2表明标记的生长素在根部的运输方向为____，BL可以____（促进/抑制）生长素运输，且对____ （运输方向）的作用更显著．

实验三：PIN蛋白与生长素的运输有关，研究人员测定了BL处理的根部组织中PIN蛋白基因表达的相关指标．结果如表所示．

（3）上述系列实验结果表明，油菜素内酯通过影响根细胞中____ ，从而影响生长素在根部的____和分布，进而影响了生长素的生理作用．