208, Teratomas are unusual forms of cancer because they are composed of tissues such as tooth and bone not normally found in the organ in which the tumor appears.
A. because they are composed of tissues such as tooth and bone
B. because they are composed of tissues like tooth and bone that are
C. because they are composed of tissues, like tooth and bone, tissues
D. in that their composition, tissues such as tooth and bone, tissues
E. in that they are composed of tissues such as tooth and bone, tissues
答案是E, 我选的是B, 我觉得E选项tissues后面少了一个being, :, tissues not normally being found in the organ in which the tumor appears. | 
