5. Are you a member of fitness club?
你是健身俱乐部的成员吗？
还能这样说：
Do you belong to the health club?
Are you admitted as a member of the fitness club?
谚语：
He is not fit to command others that cannot command himself.
正人先正己。
6. I find great fun in aerobic activity.
我发现有氧健身活动其乐无穷。
还能这样说：
Aerobic activity is very interesting.
Aerobic activity is full of fun.
应用解析：
like fun 有力地；迅速地；十分；
have fun 作乐，玩乐；
do not see the fun of 不以为有趣；
for fun 开玩笑，不是认真的；
make fun of sb. 嘲笑；取笑
7. We should warm up before doing some exercises.
开始做运动前，我们都应该热身。
还能这样说：
We should do warm-up when we begin to do some exercises.
Each time we work out we should begin with warm-up exercises.
谚语：
A borrowed cloak does not kept one warm.
借来的斗篷不暖身。
8. Bodybuilding is becoming more and more popular in my town.
健身在我家乡变得越来越流行。
还能这样说：
It is very popular to build up bodies in my town.
Working out is becmoing increasingly popular in my town.
应用解析：
come to town 到城里来；到场；
hit town 来到城里；
the sea-born town 水都威尼斯；
out of town 不在城里；在乡下