我的抗议信只是杯水车薪。

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

自然这只是杯水车薪，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.

与所需的总资金相比，这笔捐款只是杯水车薪。

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