She was a casual ___________ of my family in Vienna.
病毒具有宿主特异性,即某一种病毒仅能感染一定种类的微生物、植物或动物
Employees who fit in with the corporate culture are likely to be less productive.
一个病毒的毒粒内既含有DNA又含有RNA。
丁肝病毒 实际上 就是一种寄生在乙肝病毒中的类病毒