[误] Ignorance and negligence have caused this mistake.

[正] Ignorance and negligence has caused this mistake.

注：两个以上的主语用 and 连起来表示一个单纯的目的或观念时，动词要用单数才对。他例如 Truth and honesty is always the best policy. Slow and steady wins the race. Bread and butter is his abomination.