英语语法分析

The main risk in xenotransplantation is the transmission of diseases.

异种移植存在的主要危险是传播疾病。

However, the science of xenotransplantation is much less straightforward.

然而，异种移植科学远不是那么简单。

Objective To investigate the role of direct and indirect recognition in pig to man xenotransplantation.

目的探讨直接识别和间接识别在异种移植中的作用。