[A] activity [B] adopting [C] care [D] colleagues [E] compensated

[F] even [G] examined [H] familiar [I] injecting [J] rather

[K] reckon [L] research [M] similar [N] soared [O] synthetic

When children hit puberty (青春期), their ability to learn a second language drops. Why is this? Sheryl Smith and her【C1】_____at the State University of New York now【C2】_____that all of these behavioural changes could be due to a temporary increase in a chemical receptor that inhibits brain activity in an area responsible for learning.

In 2007, Smith’s team discovered that the number of these receptors【C3】_____in mice when they hit puberty, before falling back in adulthood. In their latest study, Smith’s team set about finding out if these receptors’ changes in mice might lead to impaired learning abilities,【C4】_____like those seen in pubescent humans.

The group【C5】________the hippocampus (海马体) in mice’s brains. Sure enough, pubertal mice had seven times as many of the receptors as infant mice. In adulthood, the number of these receptors fell back to an intermediate level.

Smith reckons that the same mechanism might underlie the learning deficits teenagers experience. Cheryl Sisk at

Michigan State University at East Lansing agrees that “mice’s puberty is【C6】________to human puberty, although the timescale is different”.

In a further experiment, Smith found that she could remove the learning deficits by【C7】________pubertal mice with THP.

Smith suggests that in her most recent experiment, giving extra THP to pubertal mice increased their brain activity and that this activity may have【C8】________for their learning deficits.

Smith suggests that a【C9】_____form of THP could be developed for teenagers with learning difficulties, although she acknowledges that【C10】_____would need to be taken not to create any new problems.

【C4】