1. 你的句子：The boat settled into the mud at a 35 degree / an angle of 35 degrees. 船身呈35度角倾斜陷入烂泥中。

2. 请核对原文，应该是：

The boat settled into the mud at a 35 degree angle / an angle of 35 degrees. 船身呈35度角倾斜陷入烂泥中。

3. a 35 degree angle 中的 35 degree 是定语，所以 degree 不用复数。类似的例子如：

(1) The boat is now leaning at a 30 degree angle. 船正以30度角倾斜。

(2) Place the shelf at a 90 degree angle to the wall. 把这个架子与墙成90 度角放置。

(3) He took up a 10 year lease on the house at Rossie Priory. 他签了一份10年租约，租下了罗茜大宅的房子。

(4) They made a 3,000 mile detour simply to prove a point. 他们绕行3,000英里只是为了证明自己能够做到。

(5) The new head of state should be chosen by an 87 member representative council. 新的国家元首应该由包括87名成员的代表委员会选出。