The animal only came out at night, _19 the scientists did some other studies in the day. _20 them,there was a famous scientist named Walter. Every day,he would spend an hour sitting at the desk and putting all his equipment（设备）in the _21 place.He did this carefully.But other scientists laughed at him because they thought Walter was just wasting _22.
One night,the animal appeared _23.The scientists heard its call.But the call didn't last long.The animal was frightened by the _24 made by the scientists while they were scrabbling（忙乱地找）for their cameras and notebooks.
On the next morning,the scientist _25 their fingings.Some had tried to record its call,others had noted down how it moved,and the luckiest one had even photographed parts of its tail and legs.They all congratulated each other on what they had found.However,when they saw what Walter had,they were very surprised. _26 had taken several complete（完整的）photos,the record of the animal's cry and notes about the animal.
They ran to congratulate Walter.They now understood the importance of keeping things in order.Because of that,Walter could find everying quickly in the dark.
17.A.feed B.study C.catch D.kill
18.A.relaxed B.tired C.excited D.surprised
19.A.but B.or C.and D.so
20.A.Among B.Beside C.Against D.Except
21.A.clean B.right C.safe D.pubilc
22.A.space B.money C.food D.time
23.A.angrily B.immediately C.suddenly D.quickly
24.A.plans B.noises C.records D.mistakes
25.A.compared B.counted C.sorted D.kept
26.A.They B.It C.He D.You