I'm not good at history.

我不擅长历史。

I'm not good at writing letters.

我不擅长写信。

I'm not good at running, but I like football best!

我不擅长跑步，但我最喜欢足球！

Although he was a good sportsman, Juan was not good at basketball.

尽管他是一个优秀的运动员，胡安不擅长篮球。

I'm not good at science, but I like the class very much.

我不擅长科学，但我非常喜欢这门课。

I am not good at math.

我不擅长数学。

He is not good at sports.

他不擅长运动。

I am not good at drawing.

我不擅长画画。

She is not good at cooking.

她不擅长做饭。

They are not good at singing.

他们不擅长唱歌。