Is it okay to use your laptop on the bed if you put a book underneath for ventilation?

Is it okay to use your laptop on the bed if you put a book underneath for ventilation?

Yep. A hard surface is important so as not to block the ventilation slots on the underside, but a hard enough book is sufficient for this.

Yes / Yes. That goes well without a book. Depending on the laptop (for example MacBook and Surface Book), a book doesn't even bring anything.

As long as the ventilation slots are free and can draw in and expel enough air, it's ok.

So also make sure that the book doesn't block the ventilation slots.