उसे मकान मालिक पर शक है।

Because Hindi often uses a dative experiencer structure for feelings, sensations, and mental states.

So instead of saying something like वह शक करता है in this pattern, Hindi says:

• उसे ... शक है
  = To him/her ... there is suspicion

Here, उसे means to him / to her and marks the person who has the feeling or suspicion.

So:

• वह = he/she
• उसे = to him/her

With शक है, Hindi normally uses को-marking on the experiencer:

• मुझे शक है = I suspect / I have doubts
• उसे शक है = he/she suspects / has doubts
• हमें शक है = we suspect

उसे is the oblique form of वह with को built in.

It can mean:

• to him
• to her
• sometimes that person in context

In this sentence, it does not show gender, so by itself उसे could refer to either a man or a woman.

Compare:

• वह = he / she
• उसको / उसे = to him / to her

Both उसको and उसे are correct. उसे is just the shorter, very common form.

Because शक होना commonly takes पर to mark the person or thing that is being suspected.

So the pattern is:

• X को Y पर शक है
• literally: X has suspicion on Y
• natural meaning: X suspects Y

Examples:

• मुझे उस आदमी पर शक है। = I suspect that man.
• उन्हें अपने पड़ोसी पर शक है। = They suspect their neighbor.

This is just the normal Hindi pattern. English says suspect someone, but Hindi often says someone has suspicion on someone.

In this sentence, शक is being used like a noun: suspicion / doubt.

So शक है literally means there is suspicion or there is doubt.

That is why the sentence is built as:

• उसे ... शक है
• literally: to him/her ... suspicion is

This is a very common Hindi way to express states and feelings.

You may also hear शक करना, but शक है is extremely natural when talking about someone having suspicion.

Compare:

• मुझे उस पर शक है। = I suspect him/her.
• मैं उस पर शक करता हूँ। = I suspect him/her.

Both can work, but मुझे/उसे ... शक है is very common and often sounds more idiomatic in everyday speech.

Literally, it means:

• मकान = house/building
• मालिक = owner

So मकान मालिक literally means house owner, and in normal English this is often landlord.

It is a compound noun. Hindi often combines nouns this way.

Similar compounds:

• स्कूल मालिक would mean school owner
• दुकान मालिक = shop owner
• घर मालिक can also be used in some contexts, though मकान मालिक is very common for landlord

Because masculine nouns ending in a consonant often look the same in the direct and oblique singular.

मालिक ends in a consonant, so:

• direct singular: मालिक
• oblique singular: मालिक

No visible change.

That is why you see:

• मकान मालिक
• मकान मालिक पर

By contrast, a noun like लड़का changes:

• लड़का
• लड़के पर

So the lack of change here is normal.

Because शक is treated as singular here.

The sentence is not agreeing with उसे. It is agreeing with the thing that exists in the sentence, namely शक.

So:

• उसे शक है। = He/she has suspicion.
• उसे शक हैं। would be wrong in this context.

If you had a plural noun instead, the verb could change:

• उसे कई परेशानियाँ हैं। = He/she has many problems.

But शक here is singular, so है is correct.

The word order is flexible.

The neutral order is:

• उसे मकान मालिक पर शक है।

But you could also say:

• मकान मालिक पर उसे शक है।
• उसे शक है मकान मालिक पर।
  (less neutral, more marked, depending on context)

Hindi word order often changes for emphasis, topic, or contrast. The most basic learner-friendly pattern is:

• [person with feeling] + [target with पर] + शक है

So this sentence is a very standard arrangement.

Yes. उसे and उसको are both correct.

• उसे मकान मालिक पर शक है।
• उसको मकान मालिक पर शक है।

The shorter forms are very common in speech:

• मुझे instead of मुझको
• तुझे instead of तुझको
• उसे instead of उसको

In many everyday situations, उसे sounds a bit smoother and more natural, but उसको is completely fine.

In this sentence, suspicion is the better match.

शक can cover both doubt and suspicion, depending on context.

For example:

• मुझे उसकी बात पर शक है। = I doubt what he said / I am suspicious about what he said.
• मुझे उस आदमी पर शक है। = I suspect that man.

When the object is a person, as in this sentence, suspicion is usually the clearer English choice.

Yes.

Nothing in उसे tells you whether the person is male or female. So without context, the sentence could mean:

• he suspects the landlord
• she suspects the landlord

Hindi often leaves this kind of information to context unless another word makes it clear.

Hindi does not have articles like a, an, and the.

So मकान मालिक can mean:

• a landlord
• the landlord

The exact meaning depends on context.

That is very normal in Hindi. Learners often want a separate word for the, but Hindi usually does not need one.

Yes. Very much so.

A very useful pattern is:

• [person] + [thing/person] + पर + शक है

Examples:

• मुझे उस पर शक है। = I suspect him/her.
• उन्हें पुलिस पर शक है। = They suspect the police.
• हमें इस कहानी पर शक है। = We doubt this story.

You can also reuse the को + ... + है structure for many other states:

• मुझे भूख है। = I am hungry.
• उसे डर है। = He/she is afraid.
• उन्हें उम्मीद है। = They have hope / They expect

So this sentence teaches two important Hindi habits at once:

1. को for the experiencer
2. a noun + है for a state or feeling