No two threads will be able to execute methods against those objects at the same time (on a per-objectbasis, obviously).
不会存在两个线程同时调用该对象的方法的情况（显然是以对象为基础的）。
2
To minimize the work required on a per-objectbasis, the default should minimize the objects for which you must specify the object lifetime.
为使针对平均每个对象所需执行的工作最小化，默认设置应使需要指定生存期的对象个数最少。
3
We can define generic methods in one place and mix them into our Objects across multiple Class types while limiting access to sensitive methods on a per Objectbasis.