Input: Article: This reaction is favored at low pressures but is nonetheless conducted at high pressures (2.0  MPa, 20 atm or 600 inHg). This is because high-pressure H
2 is the most marketable product and Pressure Swing Adsorption (PSA) purification systems work better at higher pressures. The product mixture is known as "synthesis gas" because it is often used directly for the production of methanol and related compounds. Hydrocarbons other than methane can be used to produce synthesis gas with varying product ratios. One of the many complications to this highly optimized technology is the formation of coke or carbon:

Now answer this question: Besides methane, what else can be used to produce synthesis gas?

Output: Hydrocarbons

Input: Article: The new interiors sought to recreate an authentically Roman and genuinely interior vocabulary. Techniques employed in the style included flatter, lighter motifs, sculpted in low frieze-like relief or painted in monotones en camaïeu ("like cameos"), isolated medallions or vases or busts or bucrania or other motifs, suspended on swags of laurel or ribbon, with slender arabesques against backgrounds, perhaps, of "Pompeiian red" or pale tints, or stone colours. The style in France was initially a Parisian style, the Goût grec ("Greek style"), not a court style; when Louis XVI acceded to the throne in 1774, Marie Antoinette, his fashion-loving Queen, brought the "Louis XVI" style to court.

Now answer this question: What types of techniques were used to style motifs?

Output: flatter, lighter motifs, sculpted in low frieze-like relief or painted in monotones

Input: Article: In the example above, the identity and the rotations constitute a subgroup R = {id, r1, r2, r3}, highlighted in red in the group table above: any two rotations composed are still a rotation, and a rotation can be undone by (i.e. is inverse to) the complementary rotations 270° for 90°, 180° for 180°, and 90° for 270° (note that rotation in the opposite direction is not defined). The subgroup test is a necessary and sufficient condition for a subset H of a group G to be a subgroup: it is sufficient to check that g−1h ∈ H for all elements g, h ∈ H. Knowing the subgroups is important in understanding the group as a whole.d[›]

Now answer this question: What essential condition must be met for a subset of a group to be a subgroup?

Output:
The subgroup test