As we know, his father is a very famous scientist in physics. But what you don't know is that he _______ as a farmer for five years.

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   "Let's go to the petting zoo(抚爱式动物园)!"said Bonk．
    "First, let's get some food for the animals.” said Lurk．
    "I'm so happy we can feed the animals．"said Uzzle．
    "I'll get carrots for the horses．"said Lurk．
    "I'll get cabbages for the chickens．"said Uzzle．
    "I'll get corn(玉米)for the sheep，"said Bonk．
    At the zoo，Bonk put some of the corn in his bag．His bag had a small hole(洞)，but Bonk didn't know about it．Bonk and his friends played with the animals and fed them．Bonk forgot about the corn.
    On the way home，the corn dropped(落下)out．One of the sheep at the zoo followed the corn to Bonk's home．Before Bonk and his friends said goodbye to each other, they saw the sheep．
    "How do we get him back to the zoo?"asked Bonk．
    Bonk and his friends did everything．But the sheep just didn't move．
   "Mr. Sheep?" said Lurk．"You need to go back to the zoo."The sheep didn't move．
    "I know what will work!"said Bonk．Bonk put the corn along the road to the petting zoo and let the sheep eat it．The sheep moved when he ate the corn．At last ,the sheep was back at the zoo．
    "Baa!"said the sheep．
    "You're welcome．"said Bonk.
根据材料内容简要回答下列问题。

观察如图人的心脏内部结构示意图，图中①和④所指的腔分别是心脏的（　　）

对卵细胞、胚泡、受精卵、胎儿、胚胎几个生理名词，按照形成的先后排序正确的是（　　）​

下列表述中体现辩证否定观的是（　 ）