阅读下面短文，根据文章大意用所给单词的适当形式填空(未提供单词的，限填一词)，使文章意思完整、正确。
Millions of people across the world have pets. Maybe you have one and maybe some of your friends do too. A pet can be ____ special friend, and you may think of him or her as a member of the family. A pet can play with you or just be with you when you don't feel like ____ (talk).
____ (unlucky), pets can't stay with ____ (we) forever. Like all living things, they will die. Sometimes a pet dies because he or she is too old. Sometimes a pet dies ____ an accident. Sometimes a pet gets too sick ____ (live) longer. Even when an animal doctor helps, there are some problems mat just can't ____ (solve).
It's a sad thing to know a pet dies. You probably feel lonely ____ it seems like you lose a friend. You may even feel mad at the vet (兽医) for not being able to make your pet ____ (well) than it was. Maybe you feel sorry when you remember the fact that sometimes you weren't kind to your pet.
To some children, it may seem like nobody ____ (understand) what they are feeling. Someone may say to a girl, "You can get another cat." But she knows she will never have a cat just like the dead one.
Be）从最靠近核的K层电子轨道上俘获一个电子后发生衰变，生成一个锂核（
），并放出
一个不带电的中微子νe（质量不计），人们把这种衰变叫铍核的
EC衰变。核反应方程为：
。已知一个铍原子质量为m1，一个锂原子质量为m2，一个电子质量为me，光速为c，则一个铍原子核发生上述核反应释放的能量为
