1. I think it hard to learn gymnastics.
我認為學體操很難。
還能這樣說：
I think it difficult to learn gyms.
To me, it's not easy to learn gyms.
諺語：
A faithful friend is hard to find.
知音難覓。
2. I like to do calisthenics.
我喜歡做健美操。
還能這樣說：
I am fond of aerobics.
Calisthenics is my favorite.
3. The first thing before I have my breakfast is to do exercises.
我吃早飯前的第一件事是做操。
還能這樣說：
I do exercises before my breakfast.
I don't have my breakfast until I finish doing gyms.
諺語：
Cast not the first stone.
責人之前先自省。
4. Let's go and do exercises.
大家去做操吧。
還能這樣說：
It's time to do gym.
What about doing exercises?
應用解析：
let sb./sth. be 不干涉，不打擾；
let go of 松開，釋放；
let us say 比如；
to let 待租，出租