Learn Hardcore French: Je dois concentrer tous mes efforts sur ce projet. - I must focus all my efforts on this project.

Je dois is the present tense of devoir (to have to / must). It means “I have to / I must” right now or in a general, current situation.

Je dois = I must / I have to (present, current obligation)
Je devrai = I will have to (future obligation)
Je devais = I had to / I used to have to (past or habitual)
J’ai dû = I had to (completed past obligation)

In your sentence, the obligation is seen as current or general, so je dois is the appropriate choice.

Why is concentrer in the infinitive and not conjugated like je concentre?

After devoir, French uses an infinitive verb:

devoir + infinitive

So you say:

Je dois partir. = I have to leave.
Je dois travailler. = I have to work.
Je dois concentrer… = I have to concentrate…

If you conjugated concentrer (je concentre), it would break the construction:

❌ Je dois je concentre tous mes efforts… (incorrect)
✅ Je dois concentrer tous mes efforts… (correct)

What is the difference between je dois concentrer tous mes efforts and je dois me concentrer?

They’re close in meaning but not identical:

Je dois me concentrer sur ce projet.
= I need to concentrate (myself) on this project.
Focus is on your mental attention.
Je dois concentrer tous mes efforts sur ce projet.
= I have to focus all my efforts on this project.
Focus is on efforts/energy/resources being directed toward the project.

Grammatically:

se concentrer sur = reflexive verb (to concentrate / to focus)
concentrer quelque chose sur = to concentrate something on something

In your sentence, tous mes efforts is the direct object of concentrer.

Why is it tous mes efforts and not toutes mes efforts?

Because effort is masculine in French:

un effort → masculine singular
des efforts → masculine plural

The plural of tout must agree with the gender and number of the noun:

Masculine plural: tous → tous mes efforts
Feminine plural: toutes → e.g. toutes mes idées (“all my ideas”)

So:

✅ tous mes efforts (masculine plural)
❌ toutes mes efforts (would wrongly assume efforts is feminine)

Why does tous come before mes efforts instead of after, like mes efforts tous?

In French, quantifiers like tout / tous / toutes usually come before the determiner + noun group:

tous mes amis (all my friends)
toutes ses tentatives (all his/her attempts)
tous ces livres (all these books)

Putting it at the end:

❌ mes efforts tous
is not standard in modern French. Natural order is:
✅ tous mes efforts

Why is the preposition sur used: sur ce projet and not à ce projet?

Both sur and à can appear with similar ideas, but they don’t feel the same.

With concentrer / se concentrer, the most natural preposition for the idea “focus on” is sur:

concentrer tous ses efforts sur un projet
se concentrer sur un projet

Using à would sound unusual or incorrect in this specific structure.

Compare:

se consacrer à un projet = to devote oneself to a project
consacrer tout son temps à un projet = to devote all one’s time to a project

So the preposition depends on the verb:

se concentrer sur / concentrer (quelque chose) sur
se consacrer à / consacrer (quelque chose) à

Could I also say Je dois me concentrer sur ce projet instead? Is it natural?

Yes, Je dois me concentrer sur ce projet is very natural and probably more common in everyday speech.

Nuance:

Je dois me concentrer sur ce projet.
Neutral, everyday way to say “I need to focus on this project.”
Je dois concentrer tous mes efforts sur ce projet.
Slightly more formal or emphatic: you’re not just paying attention; you’re directing all your efforts there (time, energy, resources, etc.).

Both are correct; choose based on how strong or formal you want to sound.

Is the word order fixed, or could I move tous mes efforts somewhere else?

The standard, neutral order is:

Je dois concentrer tous mes efforts sur ce projet.

You can move parts around for emphasis, but it quickly sounds more literary or marked:

Je dois, sur ce projet, concentrer tous mes efforts. (more formal/emphatic)
Tous mes efforts, je dois les concentrer sur ce projet. (strong emphasis on tous mes efforts)

For normal spoken or written French, keep:

Je dois concentrer tous mes efforts sur ce projet.

Is concentrer always used with a direct object like tous mes efforts?

Yes, concentrer is transitive here: it needs something you are concentrating.

Common patterns:

concentrer tous ses efforts sur…
concentrer sa critique sur…
concentrer son énergie sur…

If you want to say “to concentrate” intransitively (without a direct object), you usually use the reflexive verb se concentrer:

Je dois me concentrer. = I need to concentrate.
Tu dois te concentrer sur tes études. = You need to focus on your studies.

Could I drop tous and just say Je dois concentrer mes efforts sur ce projet?

Yes, you can:

Je dois concentrer mes efforts sur ce projet.

That just slightly changes the nuance:

mes efforts = my efforts (neutral)
tous mes efforts = all my efforts (insists on the totality, stronger emphasis)

So the original sentence sounds more intense: you’re putting everything into this project.

Why is it ce projet and not cet projet or cette projet?

Because projet is:

masculine: un projet
starts with a consonant sound: /p/

The demonstratives are:

ce
- masculine singular noun starting with a consonant → ce projet
cet
- masculine singular noun starting with a vowel or silent h → cet homme, cet ami
cette
- feminine singular noun → cette idée
ces
- plural (both genders) → ces projets, ces idées

So:

✅ ce projet
❌ cet projet
❌ cette projet

How is this sentence pronounced, especially tous mes efforts and sur ce projet?

Approximate pronunciation (in IPA):

Je dois → /ʒə dwa/
concentrer → /kɔ̃.sɑ̃.tʁe/
tous mes efforts → /tu me.z‿e.fɔʁ/
- tous = /tu/ (the final s is silent here)
- liaison between mes and efforts: mes_efforts → /me.z‿e.fɔʁ/
sur ce projet → /syʁ sə pʁɔ.ʒɛ/

Spoken as one flow:

Je dois concentrer tous mes efforts sur ce projet.
/ʒə dwa kɔ̃.sɑ̃.tʁe tu me.z‿e.fɔʁ syʁ sə pʁɔ.ʒɛ/

Could I say something like Il faut que je concentre tous mes efforts sur ce projet instead of Je dois…? Is there a difference?

Yes, you can:

Il faut que je concentre tous mes efforts sur ce projet.

Meaning is very close (“I must / I have to…”), but there is a nuance:

Je dois…
Sounds a bit more personal and direct: “I must / I have to…”
Il faut que je…
Literally “it is necessary that I…”, slightly more impersonal or abstract obligation. Often used in spoken French as a softer or more idiomatic way to express obligation.

Both are correct and quite natural.