Given a context passage, generate a question from the passage such that its answer is shortest continous span from the passage.

Example Input: In plant, primary transcripts (pri-miRNAs) transcribed from miRNA genes by RNA polymerase II are first processed into stem-loop pre-miRNAs and further chopped into 21nt long miRNAs by RNase III-like enzyme DCL1. SERRATE (SE) protein is an essential component for miRNA processing by assisting DCL1 for accurate cleavage. Here we report the crystal structure of Arabidopsis SE core (residues 194-543) at 2.7A. SE core adopts the 'walking man-like' topology with N-terminal helices, C-terminal non-canonical zinc-finger domain and novel Middle domain resembling the leading leg, the lagging leg and the body, respectively. Pull-down assay shows that SE core provides the platform for HYL1 and DCL1 binding, whereas in vitro RNA binding and in vivo mutant rescue experiments suggest that the non-canonical zinc-finger domain coupled with C-terminal tail binds miRNA precursors. SE presumably works as a scaffold-like protein capable of binding both protein and RNA to guide the positioning of miRNA precursor toward DCL1 catalytic site within miRNA processing machinery in plant.
Example Output: Which polymerase transcribes pri-miRNAs?

Example Input: Almost all surfaces reflect some of the light that strikes them. The still water of the lake in Figure 22.9 reflects almost all of the light that strikes it. The reflected light forms an image of nearby objects. An image is a copy of an object that is formed by reflected or refracted light. If a surface is extremely smooth, like very still water, then an image formed by reflection is sharp and clear. This is called regular reflection. If the surface is even slightly rough, an image may not form, or if there is an image, it is blurry or fuzzy. This is called diffuse reflection. Both types of reflection are represented in Figure 22.10. You can also see animations of both types of reflection at this URL: [Link] In Figure 22.10, the waves of light are represented by arrows called rays. Rays that strike the surface are referred to as incident rays, and rays that reflect off the surface are known as reflected rays. In regular reflection, all the rays are reflected in the same direction. This explains why regular reflection forms a clear image. In diffuse reflection, in contrast, the rays are reflected in many different directions. This is why diffuse reflection forms, at best, a blurry image. One thing is true of both regular and diffuse reflection. The angle at which the reflected rays bounce off the surface is equal to the angle at which the incident rays strike the surface. This is the law of reflection, and it applies to the reflection of all light. The law is illustrated in Figure 22.11 and in the animation at this URL: Mirrors are usually made of glass with a shiny metal backing that reflects all the light that strikes it. Mirrors may have flat or curved surfaces. The shape of a mirrors surface determines the type of image the mirror forms. For example, the image may be real or virtual. A real image forms in front of a mirror where reflected light rays actually meet. It is a true image that could be projected on a screen. A virtual image appears to be on the other side of the mirror. Of course, reflected rays dont actually go behind a mirror, so a virtual image doesnt really exist. It just appears to exist to the human eye and brain. Most mirrors are plane mirrors. A plane mirror has a flat reflective surface and forms only virtual images. The image formed by a plane mirror is also life sized. But something is different about the image compared with the real object in front of the mirror. Left and right are reversed. Look at the man shaving in Figure 22.12. He is using his right hand to hold the razor, but his image appears to be holding the razor in the left hand. Almost all plane mirrors reverse left and right in this way. Some mirrors have a curved rather than flat surface. Curved mirrors can be concave or convex. A concave mirror is shaped like the inside of a bowl. This type of mirror forms either real or virtual images, depending on where the object is placed relative to the focal point. The focal point is the point in front of the mirror where the reflected rays intersect. You can see how concave mirrors form images in Figure 22.13 and in the interactive animation at the URL below. The animation allows you to move an object to see how its position affects the image. Concave mirrors are used behind car headlights. They focus the light and make it brighter. They are also used in some telescopes. The other type of curved mirror, a convex mirror, is shaped like the outside of a bowl. This type of mirror forms only virtual images. The image is always right-side up and smaller than the actual object, which makes the object appear farther away than it really is. You can see how a convex mirror forms an image in Figure 22.14 and in the animation at the URL below. Because of their shape, convex mirrors can gather and reflect light from a wide area. This is why they are used as side mirrors on cars. They give the driver a wider view of the area around the vehicle
Example Output: Concave mirrors are used

Example Input: Believing that success would mean total victory but that failure would mean total defeat (as the surprise attack was a desperate measure given that Later Tang was having difficulty supplying its army), he sent Lady Liu and Li Jiji back to Xingtang, and bade farewell to them, informing them that if he failed, they should gather all the family members at the Xingtang palace and commit suicide by setting fire to it.
Example Output:
In one word, how did Li Jiji die?