Question: some of the sharper and more durable blades can give up to 7 shaves without a problem.
Answer: --> Some of the sharper and more durable blades can give up to 7 shaves without a problem.

Question: gems were also used for the mosaics, which adorn the interior, and to give a striking effect of gold and resplendent colours to the domes and vaults.
Answer: --> Gems were also used for the mosaics, which adorn the interior, and to give a striking effect of gold and resplendent colours to the domes and vaults.

Question: the surprising thing is that there is quite limited variations in grammatical structures.
Answer:
--> The surprising thing is that there is quite limited variations in grammatical structures.