TTLS

quy hoc bong ttls

Tương Lai Tươi Sáng Là Sẻ Chia

IELTS Preparation Series 1, Episode 14: Junk DNA


(Bấm vào đây để xem/nghe bài kế tiếp)

Xem lời thoại bên dưới:

0:00

Hello. I'm Margot Politis. Welcome to Study English, IELTS preparation.

0:19

Today we're going to look at conditional sentences. They're sentences that use 'if'.

0:26

If you listen carefully, you'll be able to hear Dr Malcolm Simons talking about junk

0:31

DNA, the parts of DNA that people used to think were just rubbish. Listen to the different

0:37

types of sentences he uses.

0:40

Under Darwinistic notions, you would think that junk would drop off under the theory

0:48

of natural selection, just like species drop off if they hit ecological niches, which is

0:53

incompatible with survival. If they can adapt to those niches, then those that can, survive,

1:02

and those that can't, die, is the notion. If you apply that to the DNA sequence, then

1:09

the coding region genes, which survive, have a function, and by the way the non-coding

1:15

sequences have survived as well. So the proposition would have to be that if they're there, they've

1:22

got a function.

1:23

In listening to Dr Simons, you can hear that he uses a variety of sentences. This makes

1:29

for much more interesting language. You should practice using sentences of different lengths

1:34

and types, especially complex sentences.

1:38

Today we're going to look at one of the ways you can create complex sentences using an

1:43

'if clause'.

1:45

An 'if clause' is a phrase that gives a condition that's necessary for something else to happen.

1:51

They're often called conditional clauses.

1:55

If means when, provided that, or on condition that.

2:01

There are a few basic patterns for the 'if clause'.

2:05

Listen to this:

2:07

If they can adapt to those niches, then those that can, survive, and those that can't, die.

2:15

So the proposition would have to be that if they're there, they've got a function.

2:21

If they can adapt, then those that can survive.

2:26

The pattern here is: if + simple present tense verb, then ….

2:34

Then introduces a clause describing the consequences.

2:40

Look at the second example in the extract.

2:43

If they are there, they have got a function.

2:47

Notice that the then is left out in this example. Then is optional.

2:54

He could have said if they are there, then they have a function.

3:00

Let's look at some more.

3:03

If you have a university education, then you have more opportunities.

3:08

But the then is optional - you can leave it out.

3:14

If you have a university education, you have more opportunities.

3:20

Notice that this pattern can be reversed.

3:23

You have more opportunities if you have a university education.

3:29

We never include then when the pattern is reversed like this.

3:32

Let's try with the example from the story.

3:37

If they're there, they have a function.

3:39

They have got a function, if they're there.

3:43

OK, now here's the second pattern for 'if' sentences.

3:48

This is for when the suggestion is less definite, or less likely.

3:53

If you had a university education, then you would have more opportunities.

4:01

The pattern here is: if + past tense, then + would + verb.

4:11

If you had a university education, then you would have more opportunities.

4:18

We use this pattern when we are talking about the future, and about something that may not

4:23

be as likely to happen.

4:25

Compare these 2 patterns.

4:28

If you study hard, then you will pass your test.

4:33

If you studied hard, then you would pass your test.

4:37

In the first example, it's a bit like making a useful suggestion.

4:42

The second sentence is less definite, and less polite. It suggests that the person doesn't

4:48

study hard now.

4:50

So that's 2 ways of making the conditional tense - how to say that one thing will happen,

4:56

or might happen, if something else happens. There are other forms of the conditional tense

5:02

too.

5:04

If you learn them, then your English will improve!

5:07

OK, now we're going to look at ways of making opposites by using prefixes.

5:18

Listen to Dr Simons again.

5:21

Under Darwinistic notions, you would think that junk would drop off under the theory

5:28

of natural selection, just like species drop off if they hit ecological niches, which is

5:34

incompatible with survival. If they can adapt to those niches, then those that can, survive,

5:43

and those that can't, die, is the notion.

5:47

If you apply that to the DNA sequence, then the coding region genes, which survive, have

5:53

a function and by the way the non-coding sequences have survived as well.

5:58

In the passage we heard the words survive and die. They have opposite meanings.

6:05

'To survive' means to keep on living and 'to die' means to stop living. We call words with

6:12

opposite meanings, opposites.

6:15

Sometimes opposites are formed from the same word stem using prefixes. Two of the prefixes

6:22

he uses are 'in' and 'non'.

6:26

Listen:

6:27

And by the way the non-coding sequences have survived as well.

6:32

He calls the junk DNA the non-coding sequences.

6:37

Non-coding means not coding. Notice that we use a hyphen with the non- prefix.

6:44

Non- usually forms adjectives.

6:47

It means 'not in the group of', so we have non-European, non-Aboriginal or non-government.

6:57

Non- can also just means not, giving a negative sense to a word - non-fiction, non-smoking

7:04

and non-stick.

7:07

The prefix 'in' is used with adjectives as well. It also makes opposites, and means 'not'.

7:13

It forms words like: insignificant, not significant; inexpensive, not expensive; intolerant, not

7:21

tolerant.

7:23

Another common opposite prefix is un-.

7:26

We can have unfair, unattractive, unusual, unnatural.

7:33

But un- can also be used with verbs. It means that an action is reversed.

7:39

So we have undo, undress or unbend.

7:45

There aren't many rules about what sorts of words take these prefixes. You'll have to

7:50

learn most opposites one by one.

7:53

A good way to do this is to try to find out the opposite every time you come across a

7:57

new word.

8:03

Finally for today, let's have a look at how you can form adjectives from people's names.

8:08

Under Darwinistic notions, you would think that junk would drop off under the theory

8:16

of natural selection.

8:17

He says under Darwinistic notions.

8:21

Darwinistic here is an adjective, but it's got a capital letter - do you know why?

8:27

Well, that's because It comes from the name 'Darwin' - referring to Charles Darwin, who

8:32

developed the theory of natural selection.

8:36

But it's got 2 suffixes: -ist and -ic.

8:41

The -ic suffix forms adjectives that mean belonging to, or like. So 'Darwinistic' means

8:49

like a Darwinist.

8:50

But a 'Darwinist'?

8:53

Well the suffix -ist forms adjectives too, but it forms an adjective that describes a

8:59

type of person with a certain set of beliefs.

9:03

When -ist is added to people's names, it means someone who follows that person, or who believes

9:08

in what they wrote or said.

9:11

So we can have a Darwinist, someone who believes in Darwin's theories, or a Marxist, someone

9:19

who follows the writings of Marx, or a Buddhist, someone who follows the teachings of the Buddha.

9:27

Well, we're out of time for today. Remember to watch out for those opposites, and try

9:31

using 'if' clauses.

9:33

See you next time. Bye Bye.

#II21Ieltsprepseries1

         TTLS Blog
Posts are coming soon
Stay tuned...
Bài viết mới