My major interests are sporting我的兴趣是体育
My major interests are sporting.
我的主要兴趣是体育运动。
A: Whenever I have free time, I go to the gym.
A: 当我有时间的时候，我就去体育馆。
B: That's good. It keeps you fit!
B: 那好啊！它使你身强体健！
A: Yes, my major interests are sporting. I play basketball every week with friends.
A: 是的，我的主要兴趣是体育运动。我每周都和朋友打篮球。
B: You must be quite good if you play every week.
B: 如果你每周都打的话你一定打得很好。
A: Yes, not bad! It’s fun. And we play football too.
A: 是的，还不错！很好玩。我们还踢足球。
B: That's a lot exercise. You must be really fit.
B: 那有很大的运动量。你一定很强壮。
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Notes：
1. If you want to express the view that something is certain, or you are sure about something, you can use must / must, e.g. You must be very fit / You must be very fit; If you play every week, you must be good / If you play every week, you must be good.
如果你想表达某事是确定的，或者你对某事有把握，可以用must /一定。例如You must be very fit / 你一定非常强壮； If you play every week, you must be good /如果你每周都打的话你一定打得很好。
2. You can also talk generally about your hobbies or interests by saying My major interest is . . . / My main interest is . . . or My major interests are . . . / My major interests are . . . e.g. My major interest is photography / My main interest is photography.
你还可以用My major interest is . . . / 我的主要兴趣是. . . 或者 My major interests are . . . /我的主要兴趣是. . 来笼统地谈论你的爱好。例如： My major interest is photography /我的主要兴趣是摄影。
3. If something is good, you can also say informally: not bad / not bad, e.g. Mmmm, this food isn't bad: it's really nice / Mmmm, this food isn't bad； it's really nice.
如果某事是好的，你还可以非正式地说：not bad /不错。例如Mmmm, this food isn't bad: it's really nice /呣，这个食物不错；非常好吃。
信息来源：北京市民讲外语活动组委会