Answer:
'the slab seems unimpressive at first glance'
Step-by-step explanation:
Hi! The narrator uses the word 'seems' revealing his opinion of what in his eyes is the description of the slab. It's not an affirmative sentence, it's personal and doubted. To analyze the slab the narrator uses an adjective too, showing according to his vision that it's not interesting.
I hope it helps you !