Expressing similarities and differences: whereas, while, like, unlike

🔊 The teacher reads for you

« Unlike stars, which shine with their own light, the planets give off no light of their own. » « Jupiter takes more than eleven Earth years to make one complete turn around the Sun, while Earth makes its path around the Sun in just 365 ¼ days. » Astronomy is a science of comparisons: the Sun and the other stars, the planets and the stars, one planet and another. How do you say that two things are alike — or that they are not?

🎓في نهاية هذا الدرس ستكون قادرا على:

التعبير عن التشابه بـ ⁦like · similarly · likewise · both … and …⁩
التعبير عن الاختلاف بـ ⁦whereas · while · unlike · different from⁩
التمييز بين أداة يتبعها اسم ⁦(like · unlike)⁩ وأداة تتبعها جملة ⁦(whereas · while)⁩
المقارنة بين الكواكب انطلاقا من جدول أرقام

🔑يفترض هذا الدرس أنّك تتقن:

صيغ المقارنة والتفضيل ⁦(larger than · the largest)⁩
المركّب الاسميّ والجملة ⁦(noun phrase · clause)⁩
قراءة الأعداد الكبيرة والعشريّة ⁦(4,497 · 0.241)⁩

1. Alike or different? The link words

للتشابه أدوات ⁦(like · similarly · both … and …)⁩، وللاختلاف أدوات ⁦(whereas · while · unlike)⁩؛ وبعضها يتبعه اسم، وبعضها تتبعه جملة.

To express a similarity, we use like, likewise, similarly, compared with, in comparison with, both … and …, neither … nor …: « The doctor advised him to stop smoking. Similarly, he recommended him to eat much less and take plenty of exercise. » To express a difference — a contrast — we use but, however, and yet, while, whereas, unlike, conversely, on the one hand … on the other hand: « In British English, quite often means fairly, whereas it usually means very in American English. » Watch what follows the link word. Like and unlike are followed by a noun phrase (like the rest · unlike stars). Whereas and while are followed by a clause — a subject and a verb — and they join two facts in one sentence. Similarly, likewise and however open a second sentence. And in British English, different is followed by from: « Their car is different from ours. » (American English says different than.)

The Solar System — the Sun, the stars and the planets

The Sun is the very heart of our solar system. It is a typical star — one of the […] stars in our galaxy; like the rest, it is an incandescent body made up of highly compressed gases. Compared with the other stars, the Sun is of average size, but it is a giant in comparison with even the largest planets. […] The Sun is just one of the stars in our universe. When the skies are clear, we can see the twinkling of these other stars at night. Their light is less intense than that of the Sun because they are far more remote from us than any other heavenly bodies. We know that the planets of the solar system are different from the distant stars in some very important ways. Unlike stars, which shine with their own light, the planets give off no light of their own. All we can see is the light from the Sun that they reflect back to us as if they were huge mirrors in the sky. […] More distant planets have larger orbits and travel far more slowly. Jupiter, for example, takes more than eleven Earth years to make one complete turn around the Sun while Earth makes its path around the Sun in just 365 ¼ days — in other words, once a year. From the Book of Popular Science and Alan E. Nourse, The Giant Planets

Task 1 — Pick out the sentences describing similarities and differences — leave out those which contain comparatives and superlatives — and underline the link words.

استخرج جمل التشابه والاختلاف دون جمل صيغ المقارنة والتفضيل، وضع خطّا تحت أدوات الربط.

Comparison or contrast	Sentences from the text
similarity	like the rest, it is an incandescent body made up of highly compressed gases
difference	the planets of the solar system are different from the distant stars in some very important ways
difference	Unlike stars, which shine with their own light, the planets give off no light of their own.
difference	Jupiter takes more than eleven Earth years to make one complete turn around the Sun while Earth makes its path around the Sun in just 365 ¼ days

The link words: like, different from, unlike, while. Left out: « less intense than », « far more remote », « larger orbits », « far more slowly », « the largest planets » — comparatives and superlatives, which compare with the form of the adjective, not with a link word.

Link words for comparing and contrasting

	Followed by a noun phrase	Followed by a clause	Opening a second sentence
similarity	like · compared with · in comparison with	—	similarly · likewise
difference	unlike · different from	whereas · while	however · conversely · on the other hand

Both … and … and neither … nor … join two similar things: both Mercury and Venus.

Task 2 — Do you know other link words with the same functions? Use them in sentences of your own.

استعمل أدوات أخرى للتشابه والاختلاف في جمل من إنشائك.

whereas — Am.E has two past participle forms of get, gotten and got, whereas Br.E has only one, got.
similarly — Mercury has no moon. Similarly, Venus travels round the Sun alone.
both … and … — Both Mercury and Venus are closer to the Sun than the Earth.
neither … nor … — Neither Mercury nor Venus has a moon.
on the one hand … on the other hand — On the one hand, the Sun is an average star; on the other hand, it is a giant compared with the planets.

2. Comparing the planets

قارن بين الكواكب انطلاقا من الأرقام، بأدوات التشابه والاختلاف.

Four planets of the solar system

Planet	Diameter (thousand km)	Average distance from the Sun (million km)	Time for one orbit (Earth years)
Mercury	4.88	58	0.241
Venus	12.10	108	0.615
Earth	12.76	150	1
Neptune	48.6	4,497	164.8

Read 4,497 million km as four thousand four hundred and ninety-seven million kilometres.

Task 3 — Use the information in the table and the link words to describe similarities and differences between the planets.

Write four sentences: one with whereas, one with while, one with unlike, one with both … and …

Task 3 — possible answers

إجابات ممكنة : الأرقام من الجدول، والأداة المناسبة لما يتبعها.

Mercury takes 0.241 Earth years to go round the Sun, whereas Neptune takes 164.8.
Venus is 108 million km from the Sun, while Neptune is 4,497 million km away.
Unlike Neptune, Mercury is very small: its diameter is only 4.88 thousand km.
Both Mercury and Venus go round the Sun in less than one Earth year.

Notice the grammar: after whereas and while, a full clause with its verb (Neptune takes …); after unlike, a noun (Neptune).

Do this alone, in writing. Choose two planets of the table and compare them in five sentences: one with like, one with unlike, one with whereas, one with while and one with both … and …. Then check each link word: is it followed by what it needs — a noun phrase or a clause?

قارن وحدك بين كوكبين من الجدول في خمس جمل، بخمس أدوات مختلفة.

A model answer

Like the Earth, Venus is a small planet close to the Sun. Unlike Neptune, both of them take less than two Earth years to go round the Sun. Venus needs 0.615 Earth years for one orbit, whereas the Earth needs exactly one. Venus is 108 million km from the Sun, while the Earth is 150 million km away. Both Venus and the Earth have a diameter of about twelve thousand kilometres.

In the exam, similarities and differences are tested in the text exploration: you join two sentences with the link word given — whereas, while, unlike — or you rewrite a sentence with another link word without changing its meaning. Have three things ready: ① like and unlike + a noun phrase; ② whereas and while + a clause; ③ similarly, likewise, however at the start of a second sentence, with a comma. The frequent mistake: a clause after unlike — ✗ « Unlike stars shine with their own light, … » → ✓ « Unlike stars, the planets give off no light of their own ».

What I keep — To show a similarity, I use like + a noun phrase, similarly or likewise to open a second sentence, and both … and …. To show a difference, I use unlike + a noun phrase, whereas or while + a clause, and however or on the other hand between two sentences. In British English, different is followed by from. « Unlike stars, the planets give off no light of their own. »

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