4a
1 C (When I arrived, the festival was already in full swing.)
2 В (The festival is a month-long event)
3 D (My favourite festival experience was sitting out in the open, among snow-covered pine trees, under a dark night sky in a hot spa.)
4 A (It’s hilarious! No one watching can keep a straight face.)
5 D (The mood is so friendly and the locals are the perfect hosts.)
6 C (I’d heard from friends that it was one of Japan’s most popular festivals so I decided to take a look.)