Grammar – ‘To Kill Someone’ vs ‘To Have Someone Killed’

The two keys facts:

1. the person is in the room.
2. the person was in the room before you entered.

Therefore a/ and b/ and e/ are valid.
Option c/ seems confusing

Options d/ and f/ are valid, but might the confuse the listener into thinking you are not there presently.

Both solutions are possible in the first sentence. Both of them mean the same thing.

• All the different computers in this section are/have the same price.

However, with the second sentence it is grammatically correct to add the preposition "of" after are:

• These watches are of/have different designs.

It just happens that the word you picked for this example, "designs", has multiple meanings. "Design" can refer to either the scheme for how the components of the watch will work, or a decorative pattern applied to the watch. So if it is used with have, the meaning of the sentence would depend on the context. If are of is used, it could have only the first meaning.