In this task, you are given a paragraph, and your task is to construct a question from the given passage. Construct question in such a way that (i) it is well explained in the paragraph, (ii) the words may/may not be present in the paragraph, (iii) it should start with what/how/describe. Avoid creating a question that (i) is just relevant to one or two sentences, and (ii) not relevant to passage. 
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Question: Rainwater picks up carbon dioxide from the air. Rainwater goes into soil. Water with carbon dioxide percolates through soil. The water becomes a weak acid. The water dissolves limestone. Caves form where the limestone was dissolved. 

Answer: How do caves form?


Question: First you dig a whole. You place a pumpkin seed in the hole. You put some dirt over the seed. You water the seed. The seed will sprout. A vine will grow. The vine will flower. Pumpkins will appear where the flowers were. 

Answer: What are the steps involved in growing a pumpkin?


Question: The planter must select a crop. The soil is prepared properly for that specific crop. Fertilizer is added to the soil. Seeds are planted in the field. Irrigation is set up to keep the crops properly watered. The crops grow. The crops are harvested. 

Answer:
Describe the process of planting crops.