老师们好！

请看几个句子。

Some 500 tons of juicy fruit are shipped from Sicily for the occasion.

Reports say 18 million tons of rice are being stored in Thailand, that is twice as many as normal levels. 

An estimated 300 million tons of plastic is produced yearly worldwide.

Each year over 1 billion tons of solid waste is produced globally.

请问谓语单复数该如何选取。

如果tons of 修饰的是可数名词呢？比如tons of oranges，这时谓语是否一定是复数。

我上一个问题没得到答案，但是我挺想知道These changes don’t just help animals, they save human lives, too, by avoiding accidents.是不是不对的，应该改成These changes not just help animals, they save human lives, too, by avoiding accidents.