القارب ضمن الصورة.

Because Arabic usually leaves out the present-tense verb to be.

So القارب ضمن الصورة is a normal present-tense nominal sentence:

• القارب = the boat
• ضمن الصورة = within the picture

In English, you need is: The boat is within the picture.
In Arabic, for the present tense, you normally do not say a separate word for is.

If you wanted past or future, then Arabic would use a verb, for example:

• كان القارب ضمن الصورة = The boat was within the picture.
• سيكون القارب ضمن الصورة = The boat will be within the picture.

It is a nominal sentence.

The parts are:

• القارب = the subject/topic (مبتدأ)
• ضمن الصورة = the predicate/comment (خبر)

So the sentence literally has the structure:

the boat + within the picture

This is very common in Arabic: a noun first, then information about it.

ضمن means within, inside, or as part of depending on context.

In this sentence, it means something like:

• within
• inside the boundaries of

So it is a little more specific or formal than a very basic في (in).

Compare:

• القارب في الصورة = The boat is in the picture.
• القارب ضمن الصورة = The boat is within the picture / inside the picture.

In many contexts, في الصورة would sound more everyday and natural, while ضمن الصورة can sound a bit more formal or precise.

Because both nouns are definite.

• القارب = the boat
• الصورة = the picture

Arabic uses ال to mark definiteness, often corresponding to English the.

If they were indefinite, you could have something like:

• قاربٌ ضمن صورةٍ = a boat within a picture

But your sentence refers to a specific boat and a specific picture, so both are definite.

Because it comes after ضمن.

In careful grammatical analysis, ضمن is often treated like an adverb/preposition of place, and the noun after it is in the genitive.

So in fully vocalized Arabic, the sentence is:

القارِبُ ضِمْنَ الصُّورَةِ

Notice:

• القارِبُ ends in -u because it is the subject
• ضِمْنَ ends in -a
• الصُّورَةِ ends in -i because it is genitive

In everyday unvocalized writing, these endings are usually not written.

Because ص is a sun letter.

That means the l of ال assimilates to the next consonant. So:

• الصورة is pronounced roughly aṣ-ṣūra(ti), not al-ṣūra

By contrast:

• القارب keeps the l sound, because ق is a moon letter
• so القارب is pronounced al-qārib

A careful full pronunciation of the whole sentence is roughly:

al-qāribu ḍimnaṣ-ṣūrati

In pause, learners often hear something closer to:

al-qārib ḍimnaṣ-ṣūra

Not in the usual beginner sense of noun + noun possession like:

• باب البيت = the door of the house

Here, ضمن is functioning as a word of location, more like within/inside, and الصورة follows it in the genitive.

So although it may look a bit similar because the second noun is genitive, it is better for a beginner to think of ضمن الصورة as:

within the picture

rather than as a standard possessive iḍāfa phrase.

Yes, absolutely.

في الصورة is probably the more common and straightforward way to say in the picture.

The difference is roughly:

• في الصورة = in the picture
• ضمن الصورة = within the picture / inside the picture / within the bounds of the picture

So:

• If you want the simplest everyday phrasing, في الصورة is very natural.
• If you want a slightly more formal or precise tone, ضمن الصورة works well.

Yes, but the given order is the most neutral one for this sentence.

Normal order:

• القارب ضمن الصورة

This starts with the definite noun القارب, which makes it a clear nominal sentence: The boat ...

You could sometimes move the phrase for emphasis:

• ضمن الصورةِ القاربُ

But that sounds more marked or literary, not the plainest beginner form.

So for a learner, the best default is:

• القارب ضمن الصورة

In fully vocalized, careful Modern Standard Arabic, it is:

القارِبُ ضِمْنَ الصُّورَةِ

Breakdown:

• القارِبُ = nominative, because it is the subject
• ضِمْنَ = accusative-style ending on this adverb/preposition-like word
• الصُّورَةِ = genitive, because it follows ضمن

In normal printed Arabic for learners, you will often see it without short vowels:

القارب ضمن الصورة

And in everyday pronunciation outside very formal MSA, speakers often reduce or omit the case endings.