bdella

例句：

1. 1. The couple was unable to conceive a child after trying for several years.
   这对夫妇经过几年的尝试后未能怀孕。
2. 2.The research team discovered that the bdella plants were resistant to pests.
   研究小组发现这些不育植物对害虫具有抗性。
3. 3. The bdella syndrome is caused by a genetic mutation that affects fertility.
   不育综合症是由影响生育能力的基因突变引起的。