Large ulcers are more severe, have an irregular border, and can last for five to ten weeks.

大溃疡是更为严重，有一个不规则的边界，并能在过去五至十个星期。

youdao

The cells have an irregular shape with a slightly serrated border.

细胞的形状不规则，边缘呈锯齿状。

youdao

The irregular border indicated that over a long period of time each skein of yarn had been bought and hoarded whenever a dollar or two was available.

从它不规则的边沿来判断，每一束纱线都是在她手头存够一两美元的时候才买来的，而且之间隔的时间较长。

youdao