新手求助一道OG20的SC 769题！关于plus的用法

plusyyjj

题目 travelers from earth to mars would have to endure low levels of gravity for long periods of time ,avoiding large doses of radiation,plus contending with the chemicallly reactive martin soil,and perhaps even ward off contamination by martian life-form.

这句话错的，因为平行原因，答案还说plus is not a coordinating conjunction.
有大神能解答吗 plus 不能作为连词使用的嘛？但我查百度plus有conj的用法耶。？？

shiyu0217

同问

米亚要上750

好巧，我也有同样困惑

plusyyjj

travellers from earth to mars , who would have to endure low levels of gravuty for long periods of time,avoid large doses of radiation , contend with the chemically reactive martian soil,and perhaps even ward off......
  
这个句子错误原因是lack independent clause 但是这句话不是有主语旅行者，动词avoid 吗 难道不是句子吗