Less than a century ago, huge flocks of regent honeyeaters flew all over southeastern Australia. Today, they’re one of the country’s most ____1____ birds. As their numbers decreased, so did the complexity of males’ songs — with potential ____2____ to their breeding success. Now, researchers have restored the regent honeyeater’s traditional song by bringing in tutors: two wild-born male birds who ____3____ their knowledge to captive-born birds.

Fewer than 250 regent honeyeaters are ____4____ to remain in the wild, and past research has shown that many young males — unable to learn their own song from older birds — have been singing the sounds of other species or otherwise ____5____ tunes. That’s why a team of scientists worked to ____6____ the regent honeyeater’s traditional song to birds bred at two zoos in Australia.

At the start, the researchers played recorded songs to young birds — a method that ultimately ____7____, says study co-author Daniel Appleby. ____8____, Appleby and his colleagues gave other young birds real teachers. Two wild-born males who knew the correct regent honeyeater tune ____9____ their days alongside captive chicks. This time, the plan worked.

The researchers soon learned that the teacher-to-pupil proportion ____10____. “We realized that if you have too many birds to one tutor — so a big class size — they don’t learn as ____11____,” Appleby says. They began to keep groups to no more than five students per teacher, and then those who learned the song well sounded extremely ____12____ to the wild birds.

Within three years, the ____13____ of young birds that learned the traditional song went from 0 to 42 percent. Today, more than half of the zoo-bred males sing songs ____14____ to the traditional one. The researchers hope that as they ____15____ more of these animals into the wild, the population will grow and the melody will spread.

1.1.

A dangerous

B endangered

C harmful

D unpopular

解析：选B。B 考查形容词辨析。文章开头提到“Less than a century ago, huge flocks of regent honeyeaters flew all over southeastern Australia.”不到一个世纪以前，在澳大利亚东南部地区，成群结队的王吸蜜鸟曾随处可见；下文提到“As their numbers decreased”随着它们的数量减少。从前文“数量庞大”到如今数量锐减，可知该鸟类濒临灭绝，endangered（濒危的）符合语境。dangerous（危险的）、harmful（有害的）、unpopular（不受欢迎的）均与文意不符。故选B。

2.2.

A benefits

B reasons

C causes

D consequences

解析：选D。D 考查名词辨析。前文“As their numbers decreased, so did the complexity of males’ songs...”表明数量下降导致歌声变简单，后文“Within three years, the ___13___ of young birds that learned the traditional song went from 0 to 42 percent”表明能否学会正确歌声直接影响繁殖。结合可知，歌声复杂度降低会对繁殖成功带来潜在后果，consequences（后果）符合文意。benefits（益处）与语境相反，reasons、causes（原因）不表示结果。故选D。

3.3.

A passed

B gave

C offered

D provided

解析：选A。A 考查动词辨析。文中提到“two wild-born male birds who ___ their knowledge to captive-born birds”，此处表示野生雄鸟把歌声知识传授给圈养幼鸟，passed…to…（传递、传授）符合搭配与文意。gave、offered、provided虽有“给”的含义，但不表示“传承技能”。故选A。

4.4.

A guessed

B calculated

C estimated

D figured

解析：选C。C 考查动词辨析。文中提到“Fewer than 250 regent honeyeaters are ____ to remain in the wild”，对野生鸟类数量的科学表述应为“据估计”，estimated（估计）符合科研语境。guessed（猜测）过于口语，calculated（计算）强调精确运算，figured（认为）不符合。故选C。

5.5.

A complex

B traditional

C incorrect

D simple

解析：选C。C 考查形容词辨析。文中提到“many young males — unable to learn their own song from older birds ”，幼鸟无法学习本物种正确歌声，因此会唱其他物种或错误的曲调，incorrect（错误的）符合上下文。complex（复杂的）、traditional（传统的）、simple（简单的）均不贴切。故选C。

6.6.

A award

B sing

C recommend

D reintroduce

解析：选D。D 考查动词辨析。文中提到“That’s why a team of scientists worked to ____ the regent honeyeater’s traditional song to birds bred at two zoos in Australia.”，因为幼鸟不会正确歌声，科学家要把传统歌声重新传授、重新引入给圈养鸟，reintroduce（重新引入）符合文意。award（奖励）、recommend（推荐）、sing（歌唱）均不合适。故选D。

7.7.

A succeeded

B failed

C improved

D operated

解析：选B。B 考查动词辨析。文中提到“At the start, the researchers played recorded songs to young birds”，刚开始使用录音教学，后文转而使用真鸟教学，说明播放录音的方法最终失败了，failed（失败）符合语境。succeeded（成功）、improved（改善）、operated（运作）与下文转折矛盾。故选B。

8.8.

A Anyhow

B Besides

C Meanwhile

D So

解析：选D。D 考查副词辨析。上文录音方法失败，下文提到“____, Appleby and his colleagues gave other young birds real teachers.”，前后是“放弃旧方法、改用新方法”的关系，So（因此）符合逻辑。Anyhow（不管怎样）、Besides（此外）、Meanwhile（同时）均不恰当。故选D。

9.9.

A spent

B took

C cost

D paid

解析：选A。A 考查动词辨析。上文提到研究人员给幼鸟找来real teachers，既然是真正的老师，就需要和雏鸟待在一起、朝夕相处。文中提到“Two wild-born males…spent their days alongside captive chicks.”，spent their days表示“一起度过日子”，能体现老师陪伴教学的过程。took、cost、paid 不表示“度过时光”。故选A。

10.10.

A decreased

B remained

C mattered

D changed

解析：选C。C 考查动词辨析。文中提到“The researchers soon learned that the teacher-to-pupil proportion ____.”，后文解释比例过大会影响学习效果，说明师生比例很重要、有关系，mattered（要紧，重要）符合语境。decreased（减少）、remained（保持）、changed（改变）均不贴切。故选C。

11.11.

A carefully

B easily

C effectively

D happily

解析：选C。C 考查副词辨析。文中提到“if you have too many birds to one tutor — so a big class size — they don’t learn as ____”，一个老师对应太多学生时，它们就不能有效地学习，effectively（有效地）强调学习效果，符合文意。carefully（仔细地）、easily（容易地）、happily（开心地）不突出成效。故选C。

12.12.

A same

B similar

C different

D familiar

解析：选B。B 考查形容词辨析。文中提到“those who learned the song well sounded extremely ____ to the wild birds.”，学好歌声的圈养鸟叫声与野生鸟极为相似，similar（相似的）符合文意。same前必须加the，different（不同的）、familiar（熟悉的）均不合适。故选B。

13.13.

A number

B section

C quantity

D proportion

解析：选D。D 考查名词辨析。根据后面的“went from 0 to 42 percent”从 0% 上升到了 42%，可知指的是比例。A.number（数字）、B.section（部分）、C.quantity（数量）、D.proportion（比例）。故选D。

14.14.

A close

B near

C useful

D unrelated

解析：选A。A 考查形容词辨析。文中提到“more than half of the zoo-bred males sing songs ____ to the traditional one.”，超过一半的动物园雄鸟歌声接近传统歌声，close to（接近）为固定搭配。near（附近的）、useful（有用的）、unrelated（无关的）均不符合。故选A。

15.15.

A release

B free

C set

D let

解析：选A。A 考查动词辨析。文中提到“the population will grow and the melody will spread.”，即种群数量会增长，鸣唱曲调会传播，可推知研究人员要将这些鸟类放归野外，release（释放，放归）符合文意。free、set、let 不用于野生动物放归的专业搭配。故选A。