Question

grammar
5 produced by the boston - based startup superpedestrian, a new device called the copenhagen wheel can be slipped onto any bicycle to provide an electric boost. with a 350 watt motor and a 48 - volt lithium battery, it can produce more than four times the energy created by regular pedaling. ________ can use a smartphone to unlock and lock it, change gears, and select how much assistance the motor should provide.
(a) they
(b) bicycle riders
(c) he or she
(d) some
6 in 1858, frederick law olmstead and calvert vaux won a commission to redesign manhattans central park, which at that time lacked ways for pedestrians and carriages to navigate the park without disturbing one another. ________ began work later that year.
(a) it
(b) he
(c) they
(d) some
stretch: astronomers have recently discovered a stellar binary, or pair of stars, with an extremely short orbit of 51 minutes. the system appears to be a rare type of binary, known as a cataclysmic variable, ________ a hot, dense core of a burned - out star.
(a) in which a star similar to the sun orbits tightly around a white dwarf—
(b) where a star similar to the sun orbits around a white dwarf tightly,
(c) that a star similar to the sun orbits tightly, around a white dwarf
(d) which a star, similar to the sun orbits tightly around a white dwarf and

Explanation:

For question 5, the subject that can use a smartphone to control the device is "Bicycle riders", as they are the ones who would interact with the Copenhagen Wheel on their bicycles. For question 6, "Frederick Law Olmstead and Calvert Vaux" is a plural - subject, so "They" is the correct pronoun to refer to them when saying they began work later that year.

Answer:

1. B. Bicycle riders
2. C. They