lifetime
1.下面各句里的lifetime意思略有不同：
- He never left his native land in his lifetime. （一生）
- He has visited New York three times in his lifetime. （从出生到现在）
- He told me he had visited New York three times in his lifetime. （从出生到当时）
- He hopes to visit Paris once more in his lifetime. （从现在到他死亡）
- He said he hoped to visit Paris once more in his lifetime. （从当时到他死亡）
2.一个人有一个lifetime，多个人就有多个lifetimes。但说到同时代的人，用lifetime而不用lifetimes，如within our lifetime和within the lifetime of men now living。during the lifetime(s) of his three brothers里用lifetime或lifetimes都可以。
