HSK3 汉字 (131-135)

干
你在这干什么? very colloquial and folksy and depending on context, can be too direct and abrupt 你在这儿做什么 would be more standard and a bit softer in tone.
What are you doing here?

半
这个衬衫很便宜。是半价了！
This shirt is very cheap. It's half-price!

复
我不知道。这个问题很复杂。
I don't know. This problem is very complex.

阳
太阳出现在地平线上。
The sun appeared on the horizon.

算
没问题，这事就算了吧。
Don't bother, forget about this.