Sentence: Have seen some of your photos last week. It was nice (or) it is nice?

[Qwikyss]

I want to know which of the below sentence is right.

Have seen some of your photos last week. It was nice (or) it is nice?

Difference between happen and held?

Also could you please help me differentiating these words with an example. (have been, had been, has been), (of, for), (know, knew), (in, on, at)

[Kitosdad]

Have seen some of your photos last week. They were nice.

Difference between happen ................ an occurrence.

and held? ....................................... to hold in/by the arms.

I have been very ill.
He has been to the doctor.
He had been known to be violent.
Can you hold this for me please?
Of course I can.
I knew you would help.
How did you know I'd be coming?
I'll meet you in the park.
I'll be there at six o'clock.
I'll be sitting on the first bench by the gate.

Kitos.
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