I'm not sure what to do.

我不确定该做什么。

I'm not sure about that.

我不确定。

I'm not sure, but it can't be a dog.

我不确定，但它不可能是狗。

I'm not sure, his mom said slowly, looking worried.

“我不确定，”他妈妈慢慢地说，看起来很担心。

I'm not sure if it's true but I saw it on a TV show.

我不确定这是否是真的，但我在电视节目上看到的。

I'm not sure if it's true but I heard it on the radio.

我不确定这是否是真的，但我在收音机上听到的。

I haven't started yet because I'm not sure how to make it.

我还没开始，因为我不确定怎么做。

I'm not sure, but I think it might be too difficult for me.

我不确定，但我觉得这对我来说可能太难了。

I'm not sure, but you can ask for information over there.

我不确定，但你可以在那里询问信息。

I love dancing, too, but I'm not sure I'd enjoy it in such hot weather.

我也喜欢跳舞，但我不确定我会在这么热的天气里享受它。