这是一只羊

white as a sheet───苍白如纸

thin as a rake───薄如耙子

as white as a sheet───苍白如纸

hair sheep───无绒毛羊；粗毛羊

sail a ship───驾驶一艘船

the black sheep───败家子；害群败类

thin sheet───薄片，薄钢板；钢皮

But what is more curious is this: the retrovirus is closely related to a free-living virus called Jaagsiekte sheep retrovirus, which causes lung cancer in sheep and goats, but not other species.───不过更奇怪的是：这种逆转录病毒与一种游离生活的绵羊肺腺瘤逆转录病毒(可以引起绵羊和山羊患肺癌)而不是其它种更加接近。

This is a sheep and that is a goat .───这是一只绵羊，那是一只山羊。

This is a sheep.───这是一只绵羊。