雅思机经里有一个话题describe a challenging experience，其实这种“抽象”话题很好搞定，而且有90%的可能性可以跟其他的话题合并，例如an exciting activity you want to try for the first time或者something you want to for a long time but you haven't done yet. 前者是做过，后面是没做过就好了咩！
I've always wanted to go skydiving, which is risky but also exciting. I could challenge myself, push myself to the limit and overcome my fear of height. So you see, I could have a precious memory that'll be cherished for the rest of my life.
I first knew this activity from a TV show where guests were invited to try this sport to raise money for charity.
And I just immediately fell in love with this exhilarating/thrilling sport.
But I'd never had the chance to try it until I went to Australia when I was in high school. The tour guide took us to a place where we could go skydiving, I don't remember the name of that place, anyway, I signed up for it, but my mom didn't allow me to do it 'cause she thought I was too young for that sport. And that has become my greatest regret so far.
So my next travel plan would be a trip to Dubai, 'cause it's not only an exotic country where I can experience different culture, see the desert, the ocean and the palm island in person, but most importantly, it's a perfect place for skydiving.
I'll jump off a helicopter from over 3 kilometers above the ground and enjoy the free fall for about 50 seconds. Then when the parachute is open, I could have a bird's eye view of the whole city, you know, admiring the highest tower in the world and the famed palm island. And also it's the best time for taking pictures and making videos. That must be quite an experience.
而且还能套上一道之前口语机经里的题目—an expensive activity：
It might be a bit expensive, but it's definitely worth every penny.
It's definitely worth it / worthwhile.
Cherish = to keep an idea, a hope or a pleasant feeling in your mind for a long time 例如：
Cherish the memory of those days in Paris.
He cherishes the hope that one day they will meet again.
Exhilarating = very exciting and enjoyable 例如：
My first parachute jump was an exhilarating experience.
A bird's eye view of something = a view of something from a high position looking down 例如：
From the plane we had a bird's eye view of Manhattan.
Famed = very well known = renowned 例如：
Las Vegas, famed for its casinos
a famed poet and musician