أستعمل المصعد في المستشفى لأنني متعب.

أستعمل means I use or I am using. Its dictionary form is استعمل.

Yes, you can also say أستخدم in Modern Standard Arabic. Both are correct and common for to use:

• أستعمل المصعد = I use the elevator
• أستخدم المصعد = I use the elevator

In modern usage, many learners hear أستخدم very often, but أستعمل is perfectly good MSA.

Because Arabic usually does not need a separate subject pronoun when the verb already shows who the subject is.

In أستعمل, the beginning أ- tells you the subject is I. So:

• أستعمل = I use
• أنا أستعمل = I use / I do use

Adding أنا is possible, but it usually adds emphasis or contrast.

The same idea appears in لأنني: that word already includes I, so no separate أنا is needed there either.

It can mean either one, depending on context.

The Arabic imperfect tense often covers both:

• simple present: I use
• present progressive: I am using

So this sentence could mean:

• I use the elevator in the hospital because I am tired
• I am using the elevator in the hospital because I am tired

The broader situation tells you which meaning is intended.

Because الـ makes the noun definite:

• مصعد = an elevator
• المصعد = the elevator

So أستعمل المصعد means I use the elevator.

Using the definite form is natural if the elevator is a specific one already understood from the situation, such as the elevator in that hospital.

It is pronounced roughly al-miṣ-ʿad.

A few important points:

• ال = al-
• مِ = mi
• ص is an emphatic s, heavier than English s
• ع is the Arabic letter ʿayn, a deep throat sound with no exact English equivalent

So a careful pronunciation is:

الْمِصْعَد

If you are just starting, try to get close to miṣ-ʿad and improve the ع gradually.

Also, the ل in ال stays pronounced here because م is a moon letter, not a sun letter.

The final ى is called alif maqṣūra. At the end of a word, it usually sounds like a long ā.

So المستشفى is pronounced:

al-mustashfā

not al-mustashfi and not al-mustashfu.

This is just the normal spelling of the word hospital in Arabic. Even though the word changes grammatically in a sentence, its final written form usually stays the same.

في basically means in, but in many contexts it can also correspond to English at.

So:

• في المستشفى can mean in the hospital
• and sometimes, depending on context, at the hospital

Arabic often uses في where English might choose either in or at.

لأنني means because I...

It is made from:

• لأن = because
• ني = me / I in this structure

So:

• لأنني متعب = because I am tired

With full vowels, it is written:

لِأَنَّنِي

You may also see لأني, which is a common shortened form in writing. Both mean the same thing.

Because in Arabic, the verb to be is usually not stated in the present tense.

So Arabic says literally:

• لأنني متعب = because I tired

But the natural English meaning is:

• because I am tired

This is very normal in Arabic. If you wanted the past, then Arabic would use a form of كان:

• لأنني كنت متعبًا = because I was tired

متعب is the masculine singular form, so it fits a male speaker.

• متعب = tired for a male
• متعبة = tired for a female

So a female speaker would say:

أستعمل المصعد في المستشفى لأنني متعبة.

One more useful detail: without vowel marks, متعب could also be read differently in another context, but here the meaning is clearly tired.

Yes, that is grammatically correct.

Compare:

• أستعمل المصعد في المستشفى لأنني متعب.
• أنا أستعمل المصعد في المستشفى لأنني متعب.

The first is the more neutral version. The second adds أنا for emphasis, contrast, or clarity.

For example, if you want to stress I specifically, أنا can be useful.

A fully vocalized version is:

أَسْتَعْمِلُ الْمِصْعَدَ فِي الْمُسْتَشْفَى لِأَنَّنِي مُتْعَبٌ.

A few notes:

• أستعملُ ends with -u in the normal indicative form
• المصعدَ takes -a because it is the direct object
• في makes المستشفى grammatically genitive, but this word’s ending does not visibly change because of its spelling
• مُتْعَبٌ is the predicate and is nominative in full formal vocalization

In normal everyday reading, these short vowels are usually omitted.