right是强调用的副词.其实,这里就相当于：
The blanket drawn over his head like a tent.这不是句子.没谓语.
应该是这样吧
The blanket drawn right over his head is like a tent.
盖过他脑袋的毛毯就像一顶帐蓬.
类似结构：
right now
Righ there,yes.对,就在这里.