一分钟了解“do and has done”

Therefore, the infrared small target detection in heavy background clutter is considered as a challenging problem and has attracted much research attention in recent years.


主语 do and has done，and前后可以跟不同的时态，而且是直接跟谓语可以不必and之后再加主语（那样是属于and连接两个句子的情况，and之前要加逗号）。