Ответ:

с "and"

I ate a cookie and it was yummy

Once, I met a celebrate and I was shocked

Ugh.. my tea is a very sweet and hot!

с "but"

I wanted to by a balloon, but I remembered that I have no money

I slept for 9 hours, but I am exhausted

I read a book, but it wasn't interesting

Ответ:

friends and neighbors came to the party

me and my sister are the best friends

I'm not smart but I'm not stupid either

I want to buy myself a new phone but I have no money

she wants to befriend Alex but he doesn't like her