2. But, this kind of low birth level very is unstable, also inevitable has brought some social questions. 但是，这种低生育水平还很不稳定，也不可避免的带来了一些社会问题。
3. Results show, under a given coupling condition, the system will be unstable when the power overtakes its threshold. 结果表明：在一定的耦合条件下，超过某个功率阈值将导致系统不稳定；
英英解释
adj.
1. lacking stability or fixity or firmness
2. highly or violently reactive
3. affording no ease or reassurance
4. suffering from severe mental illness
5. disposed to psychological variability
6. subject to change; variable
