请问该如何判别 lack 是该搭配定冠词还是不定冠词：

1. A / The lack of a good education may prevent you from seeking a good job.

2. He was released due to a / the lack of evidence.

3. He was suffering from a / the lack of confidence.

4. A / The lack of water has become a global problem.

以上句子a / the该如何选用？从含义上似乎很难感觉出他们的差别。