“What is”, “What was” and “What percentage” questions, while the proportions of “What did”, “Why” and “Which” questions in SQuAD are larger than ours. One possible reason is that the “Why”, “What did” questions are more *complicated* to ask (sometimes involving world knowledge) and the answer spans are longer phrases of various types that are harder to identify. “What is” and “What was” questions, on the other hand, are often *safer* for the neural networks systems to ask.

The United States of America (USA), commonly referred to as the , is a federal republic composed of states, a federal district, major self-governing territories, and various possessions. ... . The territories are scattered about the . Nine time zones are covered. The geography, climate and wildlife of the country are extremely diverse.

**Q1**: What is another name for the united states of america ?

**Q2**: How many major territories are in the united states?

**Q3**: What are the territories scattered about ?

\[fig:corpus\]

![Distribution of question types of our corpus and SQuAD training set. The categories are the ones used in , we add one more category: “what percentage”.[]{data-label="fig:distr"}](./figures/distr.pdf){width="6.5cm"}

In Figure \[fig:corpus\], we show some examples of the generated question-answer pairs. 