東京大学入試問題（2020年2月26日実施）の英語１Ｂの長文読解問題（整序英作文・脱文補充）の解答・解説・和訳です。実際の受験者だけでなく、東大志望者の方も参考にしてください。＊解答と和訳は東大発表のものではありません。

以下の英文を読み. (ア). (イ)の問いに答えよ。

　Culex molestus is a subspecies of mosquito known as the London Underground mosquito. It gained this name because it was first reported during the German bombing raids of the city in 1940, when the subway tunnels were used as overnight bomb shelters. The Culex is a very common type of mosquito, and it has many forms. While they look the same as Culex pipiens, their above-ground relatives, the molestus mosquitoes behave in a very different way. Up on London's streets, the mosquitoes feed on bird, not human, blood. They need this blood meal before they can lay their eggs, and they sleep during the winter. Down in the subway, the mosquitoes suck passengers' blood and they lay eggs before feeding; they are also active the whole year round.
　Despite its name, the Underground mosquito is not unique to London, as recent studies have revealed. It lives in basements and subways all over the world, and it has adapted its ways to its human-built environment.（　ア　）and planes, its genes spread from city to city, but at the same time it also cross-breeds with local above-ground mosquitoes, absorbing genes from that source as well [   1    ] - probably only since humans began constructing underground buildings, did Culex molestus evolve.
　The evolution of the London Underground mosquito fascinates me not least because it seems such an interesting addition to evolution's standard portfolio. We all know about evolution perfecting the feathers of birds of paradise in distant jungles or the shape of rare flowers on high mountaintops. But apparently, the process is so ordinary that it is happening literally below our feet, among the dirty power cables of the city's subway system. Such a nice, unique, close-to-home example! The sort of thing you'd expect to find in a biology textbook.
　But what if it is not an exception anymore? What if the Underground mosquito is representative of all plants and animals that come into contact with humans and the human-crafted environment? What if our grip on the Earth' s ecosystems has become so firm that life on Earth is in the process of evolving ways to adapt to a thoroughly urban planet?
　In 2007, for the first time in history, there were more people living in urban than in rural areas. [   2   ]. By the mid-twenty-first century, two-thirds of the world's estimated 9.3 billion will be in cities. Mind you, that's for the entire world. In western Europe, more people have lived in cities than in the countryside since 1870, and in the US that turning point was reached in 1915. Areas like Europe and North America have been firmly on the way to becoming urban continents for more than a century. A recent study in the US showed that each year, the average distance between a given point on the map and the nearest forest increases by about 1.5 percent.
　In ecological terms, the world has never seen the situation that we find ourselves in today: a single large animal species completely occupying the planet and turning it to its advantage. At the moment, our species appropriates fully one-quarter of the food that all of the world's plants
produce and much of all the world's fresh water. Again, this is something that has never happened before. No other species that evolution has produced has ever been able to play such a central ecological role on such a global scale.
　[　3　]. By 2030, nearly 10 percent of the land on the planet will be densely populated, and much of the rest covered by farms, fields, and plantations which humans have shaped. Altogether a set of entirely new habitats, the likes of which nature has not seen before. And yet, when we
talk about ecology and evolution, about ecosystems and nature, we are stubbornly ignoring the human factor, focusing our attention instead on that diminishing fraction of habitats where human influence is still very small.
　Such an attitude can no longer be maintained. It's time to acknowledge the fact that human actions are the world's single most influential ecological force. Whether we like it or not, we have become fully integrated with everything that happens on this planet. [　4　]. Out in the real world, however, the threads of human activity are tightly woven into nature's fabric. We build cities full of novel structures made of glass and steel. We pump greenhouse gases into the air that alter the climate; we release non-native plants and animals, harvest other species, and use a variety of natural resources for our own needs. Every non-human life form on Earth will come across humans, either directly or indirectly. And, mostly, such encounters are not without consequence for the organism in question. They may threaten its survival and way of life. But they may also create new opportunities, as they did for the ancestors of Culex molestus.
　So what does nature do when it meets challenges and opportunities? It evolves. If at all possible, it changes and adapts. The greater the pressure, the faster and more widespread this process becomes. As subway passengers know all too well, in cities there is great opportunity, but also great competition. Every second matters if you want to survive, and nature is doing just that. [   5   ].

注
mosquito 蚊
ecosystem 生態系

(ア) 下に与えられた語を正しい順に並べ替え，空所(ア)を埋めるのに最も適切な表現を完成させ，記述解答用紙の1(B)に記入せよ。なお文頭の語は大文字で始めよ。

cars 　get 　in 　mosquitoes 　thanks 　that 　to 　trapped

(イ) 空所[ 1 ]~ [ 5 ]に入れるのに最も適切な文を以下のa)~ g)より一つずつ選び，マークシートの(1)~ (5)にその記号をマークせよ。ただし，同じ記号を複数回用いてはならない。

a) And it has also become clear that all this has happened very recently
b) Otherwise，it may not be possible to reverse some of the changes we are imposing on Earth
c) Perhaps in our imaginations we can still keep nature divorced from the human environment
d) Since then, that statistic has been rising rapidly
e) So, our world is becoming thoroughly human-dominated.
f) While we have all been focusing on the vanishing quantity of untouched nature, urban ecosystems have been rapidly evolving behind our backs
g) Yet the urban evolutionary rules are beginning to differ more and more from the ones we find in the natural world

↓ここからが有料記事になります（語彙・語句、解答解説、和訳）。ご了承ください。和訳に関しては、現時点（2020.2.28）で発表しているサイトおよび出版物はありません。