Hundred or hundreds?

There are ____________________ ____________________ and ____________________ - ____________________ days in a whole year .

Last weekend's charity event drew ____________________ ____________________ ____________________ participants .

I saw ____________________ of people running in the marathon .

You can finish this video game in ____________________ a hundred hours .

I've studied this topic ____________________ ____________________ times .

I still have ____________________ ____________________ places to visit before I get older .

I love experimenting with ____________________ ____________________ new recipes .

The museum features an impressive exhibit with ____________________ ____________________ ____________________ artifacts .

I've had the privilege of mentoring ____________________ ____________________ bright and enthusiastic students ,

I've attended ____________________ ____________________ ____________________ workshops and conferences .