Pastikan pintu depan terkunci sebelum tidur.

Pastikan is the command form here: Make sure / Ensure.

The verb is memastikan = to make sure, to ensure. In Indonesian, commands often use the base form without the meN- prefix, so:

• memastikan = to ensure
• pastikan = ensure / make sure

So Pastikan pintu depan terkunci means Make sure the front door is locked.

Yes. Indonesian often leaves out the subject in commands because it is understood.

So this sentence implicitly means:

• (You) make sure the front door is locked before sleeping.

If you wanted to say the subject explicitly, you could say:

• Pastikan Anda mengunci pintu depan sebelum tidur.
• Pastikan kamu mengunci pintu depan sebelum tidur.

But in normal instructions, leaving it out is very common.

In Indonesian, the usual order is:

• noun + modifier

So:

• pintu = door
• depan = front

Together, pintu depan = front door

This is very normal Indonesian word order. English often puts the modifier first, but Indonesian usually puts it after the noun.

More examples:

• rumah besar = big house
• mobil baru = new car
• kamar tidur = bedroom

Terkunci means locked or in a locked state.

It comes from kunci = lock / key, with the prefix ter-. In many cases, ter- can show a state or condition. Here, terkunci describes the condition of the door: it is locked.

So:

• pintu depan terkunci = the front door is locked

In this sentence, the important idea is the resulting state, not the action itself.

This is a very common question.

• terkunci = locked, in a locked state
• dikunci = locked by someone / was locked

In many everyday situations, both can work, but the nuance is slightly different:

• Pintu depan terkunci focuses on the state: the door is locked.
• Pintu depan dikunci focuses more on the action done to it: the door was locked.

In this sentence, terkunci sounds natural because after Pastikan, you are checking the condition of the door.

Because Indonesian often does not use a copula like is / are in the present tense.

So where English says:

• The front door is locked

Indonesian simply says:

• Pintu depan terkunci

This is completely normal. Indonesian often makes full sentences without a word equivalent to is.

Literally, sebelum tidur means before sleeping.

But in real usage, it often means before going to bed or before you go to sleep, depending on context. In this sentence, the natural English meaning is usually:

• Make sure the front door is locked before you go to bed.

So even though tidur literally means sleep, the phrase is commonly understood more broadly.

Because Indonesian often omits subjects when they are already clear from context.

So:

• sebelum tidur = before sleeping / before you sleep

If you wanted to make it explicit, you could say:

• sebelum Anda tidur
• sebelum kamu tidur

But the shorter version is very natural and common.

Yes, and that is also very natural.

Adding sudah gives the sense of already or has already become:

• Pastikan pintu depan terkunci sebelum tidur = Make sure the front door is locked before bed.
• Pastikan pintu depan sudah terkunci sebelum tidur = Make sure the front door is already locked before bed.

The version with sudah stresses completion a bit more.

Good question. The meanings are close, but not identical.

• Kunci pintu depan sebelum tidur. = Lock the front door before bed.
• Pastikan pintu depan terkunci sebelum tidur. = Make sure the front door is locked before bed.

The first one gives a direct action to do. The second one focuses on checking or ensuring the final result.

So Pastikan ... terkunci is a little broader: maybe you lock it yourself, or maybe you just check that it has been locked.

It is fairly neutral and works well as an instruction or reminder.

It is not rude, but it is a direct imperative. If you want to make it softer or more polite, you can add words like:

• Tolong pastikan pintu depan terkunci sebelum tidur. = Please make sure the front door is locked before bed.
• Harap pastikan pintu depan terkunci sebelum tidur. = Please ensure the front door is locked before bed.

So the original sentence is perfectly normal, especially in written reminders or instructions.

Sometimes, yes, depending on context.

Pastikan literally means make sure / ensure, but in real life that often includes the idea of checking. So in this sentence, it can imply:

• check whether the door is locked
• if not, lock it

So Pastikan is broader than just check and broader than just lock. It means making sure the desired condition is true.

Not always.

With ter-, Indonesian can sometimes express a resulting state without focusing on whether it was intentional. So terkunci can simply mean locked as a condition.

In everyday use, pintu terkunci usually just means the door is locked. The sentence is not really concerned with how it became locked, only that it is in that state.