The influence of climate on crops are self-evident.
气候对农作物的影响是不证自明的。（不可数）
What are the influences of TV ads on us?
电视广告对我们的影响是什么？（可数）
News media have a great influence on people's mind.
新闻媒介对人的思想有很大的影响。
I don't want to influence you. You must decide for yourself.
我不想影响你。你必须自行决定。