我的抗议信只是沧海一粟。

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

自然这只是沧海一粟，但我们可以希望其他人会模仿我们的行为。

Naturally it is ___a ___drop ___in ___the ___ocean, but we can hope that the others will imitate our behaviour.

这笔捐款与所需总资金相比只是沧海一粟。

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