Where a testamentary successor or legatee predeceases the testator ;

遗嘱继承人、受遗赠人先于遗嘱人死亡的；

For where a testament is , there must also of necessity be the death of the testator .

凡有遗命，必须等到留遗命的人死了。

Testator may appoint a testamentary executor .

遗嘱人可以指定遗嘱执行人。

Article 20 a testator may revoke or alter a will he previously made .

第二十条遗嘱人可以撤销、变更自己所立的遗嘱。

A will needs the signature of the testator and two witness .

一份遗嘱需要立遗嘱人和两个证人的签字。