我的抗议信只是沧海一粟。

My letter of protest was just ___a ___drop ___in ___the ___ocean.

我知道我只是沧海一粟，但我相信这是唯一的方式，我的方式，来为改善墨西哥的教育做出贡献。

I know I am ___a ___drop ___in ___the ___ocean, but I'm convinced it's the only way, my way, of contributing to improve education in Mexico.

与项目所需资金相比，这笔捐款只是沧海一粟。

The donation was ___a ___drop ___in ___the ___ocean compared to the funds needed for the project.