题目

完形填空Therewas once an elephant who wanted to be a photographer. How his friends wouldlaugh when they heard him talk about it!How1,said some, there aren't any cameras for elephants!Whata waste of time, others would say, there's nothing to photographhere anyway...Butthe elephant kept following his2, and, piece by piece, he succeeded incobbling together some small old junk and spare parts, and finally made aso-called camera. To make the camera work, the elephant had to3everythinghimself, from a button he pressed with the end of his trunk—the long nose, to alarge amount of iron used for m如图是人体进行消化和吸收、循环、呼吸、排泄等生理活动的部分结构示意图，请据图回答下列问题：（[]中填数字或字母，横线处请用文字作答）（1）图一中[______]分泌的消化液，不含消化酶，可以乳化脂肪。（2）在图二心脏的结构中，心脏壁最厚的是[______]，与其相连的血管是______。（3）图三中a、b表示肺泡与血液之间的气体交换过程，那么a表示的气体是______（填“氧气”或“二氧化碳”）。（4）下表中的三种样品是从上图四中的不同部位取出的血浆、原尿、尿液成分表（健康人）。成分水蛋白质葡萄糖尿素样品A√××√样品B√×√√样品C√√√√据表从图四中④和⑥处取出的样品分别是上表中的样品______和______。