两道语法题,求助

13. _________relatively costly, the diesel engine is highly efficient and needs servicing infrequently.
(A) Even
(B) It is
(C) Even though
(D) There is

Even though 和Even啥区别?

30. The field of dynamics in physics is concerned with a particle’s motion in relation to the forces acting it.

我想问一下RELATION 为什么不改成RELATING?
ACT在这里是不及物

13. even 不能引导从句，even though可以

这里应该是：Even though it is relatively costly，省略了 it  is。

30. in relation to      adv. 涉及，关于，与...相