Three million tons of coal was/were exported last year.A ton of apple has/have been sold.（应该是 a ton of apples 不小心打错了）

Three million tons of coal was/were exported last year.A ton of apple has/have been sold.（应该是 a ton of apples 不小心打错了）
Three million tons of coal was/were exported last year.A ton of apple has/have been sold.
（应该是 a ton of apples 不小心打错了）

Three million tons of coal was/were exported last year.A ton of apple has/have been sold.（应该是 a ton of apples 不小心打错了）
第一个选were
第二个选have
原因：
这道题涉及的英语语法是主谓一致,主语的单复数要与谓语的单复数形式一致.
并遵循就近原则,即谓语动词的单复形式取决于最靠近它的词语.
一般来说,不可数名词用动词单数,可数名词复数用动词复数.
但当不可数名词前有表示数量的复数名词时,谓语动词用复数形式.
虽然coal是不可数名词,但是coal前面有表示数量的复数名词tons.
看完我的详细解释在去看1楼的,应该会记得更劳,

Three million tons of coal were exported last year. A ton of apple has been sold.
three million tons 是复数，后面应接were，were 是动词b的过去式的复数形式。
a ton of apple,是单数，后面应接has been...has been sold 是被动语态。has 是have的第三人称单数形式

a ton of apple,是单数，后面应接has been...has been sold 是被动语态。has 是have的第三人称单数形式 have 可数名词看可数名词

were 不可数名词看前面的量词
have 可数名词看可数名词