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

[Q]: Modeled after US hot website.com, group buying websites are now popular in China. These websites use the power of group buying to get competitive discounts for a daily deal on some best stuff to do, see, eat and buy in the cities across China. Discounts are available within just one click. Zhao lei, a software engineer in Beijing, loves the one-hour lunch break at noon,as it is the best time for him to check "today's special" at his favorite group buying websites . Sometimes he searches for great deals at directory sites devoted to the new shopping space. Zhao spends around 800 yuan($117.65) on group buying every month, mostly to buy food coupons for eating at some nice restaurants and occasionally to find something fun to do. " I love group buying. In addition to the competitive discounts it offers, it helps me get something fun, exciting and new, and such surprises give me a reason to try something new," he said. When he finds a really good bargain, he will send the link to friends or colleagues through MSN,QQ, or e-mail, or share the information at some social networking websites. In doing so, he often gets a certain cut off the price. At some sites, buyers are invited to leave notes about what they want to buy and the website will consider it if similar applications reach a certain number. That is how Zuo got her digital camera after waiting for two months. "It is cool. I want to buy a new digitgal camera for my trip to Switzerland this winter, but I never expected such cheap prices!" Zuo said.
[A]: What is the passage mainly about?


[Q]: Many different cellular pathways have evolved to protect the genome from the deleterious effects of DNA damage that result from exposure to chemical and physical agents. Among these is a process called transcription-coupled repair (TCR) that catalyzes the removal of DNA lesions from the transcribed strand of expressed genes, often resulting in a preferential bias of damage clearance from this strand relative to its non-transcribed counterpart. Lesions subject to this type of repair include cyclobutane pyrimidine dimers that are normally repaired by nucleotide excision repair (NER) and thymine glycols (TGs) that are removed primarily by base excision repair (BER). While the mechanism underlying TCR is not completely clear, it is known that its facilitation requires proteins used by other repair pathways like NER. It is also believed that the signal for TCR is the stalled RNA polymerase that results when DNA damage prevents its translocation during transcription elongation. While there is a clear role for some NER proteins in TCR, the involvement of BER proteins is less clear. To explore this further, we studied the removal of 7-methylguanine (7MeG) and 3-methyladenine (3MeA) from the dihydrofolate reductase (dhfr) gene of murine cell lines that vary in their repair phenotypes. 7MeG and 3MeA constitute the two principal N-methylpurines formed in DNA following exposure to methylating agents. In mammalian cells, alkyladenine DNA alkyladenine glycosylase (Aag) is the major enzyme required for the repair of these lesions via BER, and their removal from the total genome is quite rapid. There is no observable TCR of these lesions in specific genes in DNA repair proficient cells; however, it is possible that the rapid repair of these adducts by BER masks any TCR. The repair of 3MeA and 7MeG was examined in cells lacking Aag, NER, or both Aag and NER to determine if rapid overall repair masks TCR. The results show that both 3MeA and 7MeG are removed without strand bias from the dhfr gene of BER deficient (Aag deficient) and NER deficient murine cell lines. Furthermore, repair of 3MeA in this region is highly dependent on Aag, but repair of 7MeG is equally efficient in the repair proficient, BER deficient, and NER deficient cell lines. Strikingly, in the absence of both BER and NER, neither 7MeG nor 3MeA is repaired. These results demonstrate that NER, but not TCR, contributes to the repair of 7MeG, and to a lesser extent 3MeA.
[A]: Which gene strand is targeted by transcription-coupled repair (TCR)?


[Q]: A solar eclipse occurs when the new Moon passes directly between the Earth and the Sun (Figure 1.1). This casts a shadow on the Earth and blocks Earths view of the Sun. A total solar eclipse occurs when the Moons shadow completely blocks the Sun (Figure 1.2). When only a portion of the Sun is out of view, it is called a partial solar eclipse. Solar eclipses are rare and usually only last a few minutes because the Moon casts only a small shadow (Figure 1.3). As the Sun is covered by the Moons shadow, it will actually get cooler outside. Birds may begin to sing, and stars will become visible in the sky. During a solar eclipse, the corona and solar prominences can be seen. A solar eclipse occurs when the Moon passes between Earth and the Sun in such a way that the Sun is either partially or totally hidden from view. Some people, including some scientists, chase eclipses all over the world to learn or just observe this amazing phenomenon. A solar eclipse shown as a series of pho- tos. Click image to the left or use the URL below. URL: A lunar eclipse occurs when the full moon moves through Earths shadow, which only happens when Earth is between the Moon and the Sun and all three are lined up in the same plane, called the ecliptic (Figure 1.4). In an eclipse, Earths shadow has two distinct parts: the umbra and the penumbra. The umbra is the inner, cone-shaped part of the shadow, in which all of the light has been blocked. The penumbra is the outer part of Earths shadow where only part of the light is blocked. In the penumbra, the light is dimmed but not totally absent. A total lunar eclipse occurs when the Moon travels completely in Earths umbra. During a partial lunar eclipse, only a portion of the Moon enters Earths umbra. Earths shadow is large enough that a lunar eclipse lasts for hours and can be seen by any part of Earth with a view of the Moon at the time of the eclipse (Figure 1.5). A lunar eclipse does not occur every month because Moons orbit is inclined 5-degrees to Earths orbit, so the two bodies are not in the same plane every month.
[A]:
during a solar eclipse