I'm glad I ran into you. Where have you been hiding lately?

我很高兴碰见你，你躲到哪里去了？

You hit it.

你说对了。

How come you speak such good English?

你为什么能说这么好的英语呢？

She is at the top of her class.

她在班里名列前茅。

I'm very tired.

我很累了。

If you watch carefully you will see how to do it.

你若细心观察，就会知道怎么做这件事。