IN: For a thin lens in air, the focal length is the distance from the center of the lens to the principal foci (or focal points) of the lens. For a converging lens (for example a convex lens), the focal length is positive, and is the distance at which a beam of collimated light will be focused to a single spot. For a diverging lens (for example a concave lens), the focal length is negative, and is the distance to the point from which a collimated beam appears to be diverging after passing through the lens.
is the focal length of a convex lens negative?

OPTIONS:
- no
- yes

OUT: no

IN: Historically, the distinction is made based on qualitative differences in properties. Matter in the solid state maintains a fixed volume and shape, with component particles (atoms, molecules or ions) close together and fixed into place. Matter in the liquid state maintains a fixed volume, but has a variable shape that adapts to fit its container. Its particles are still close together but move freely. Matter in the gaseous state has both variable volume and shape, adapting both to fit its container. Its particles are neither close together nor fixed in place. Matter in the plasma state has variable volume and shape, but as well as neutral atoms, it contains a significant number of ions and electrons, both of which can move around freely.
a solid is a state of matter that has a shape and volume?

OPTIONS:
- no
- yes

OUT: yes

IN: East St. Louis is a city in St. Clair County, Illinois, across the Mississippi River from St. Louis, Missouri, in the Metro-East region of Southern Illinois. Once a bustling industrial center like many cities in the Rust Belt, East St. Louis has been severely affected by loss of jobs due to deindustrialization during the second half of the 20th century. In 1950, East St. Louis was the fourth largest city in Illinois when population peaked at 82,366. As of the 2010 census, the city had a population of 27,006, less than one-third of the 1950 census.
is east st louis part of st louis?

OPTIONS:
- no
- yes

OUT: no

IN: Toilet paper when used with a toilet roll holder with a horizontal axle parallel to the floor and also parallel to the wall has two possible orientations: the toilet paper may hang over (in front of) or under (behind) the roll; if perpendicular to the wall, the two orientations are right-left or near-away. The choice is largely a matter of personal preference, dictated by habit. In surveys of US consumers and of bath and kitchen specialists, 60--70 percent of respondents prefer over.
is there a right way to put on toilet paper?

OPTIONS:
- no
- yes

OUT:
no