hobby-horse
n. 反复唠叨的话题; 喜爱的话题; 老调重弹
例句与用法：
His hobby is entomology.
他爱好昆虫学。
She hasn't got any hobbies unless you call watching TV a hobby.
她没有任何嗜好--除非把看电视也算作嗜好的话。
Angling is his main hobby.
钓鱼是他的主要爱好。
Some people like horseback ride, but I prefer golf as a hobby.
一些人喜欢马术，但是我宁愿把打高尔夫球作为一种业余爱好。
My hobby is a good safety-valve for the tension that builds up at work.
我用业余爱好来消除工作中产生的紧张情绪。
One of my hobbies is painting.
我的业余爱好之一是画画。
词形变化：