Her excuse just doesn't add up.
她的辩解就是无法自圆其说.
What he said always can add up!
他总是能自圆其说!
If I were you,I would take Tom's advice,what he said was add up.
如果我是你,我就会采纳汤姆的意见,因为他说的言之有理.
Although each individual consignment of data is tiny,they add up.
尽管每一次数据发送量本身很小,但它们加起来（就很大了）.