Complement of Result is a grammar pattern that makes Mandarin easier to learn.
|Kàn (look)||+ dào =||Kàndào (see)|
|Zhǎo (search)||+ dào =||Zhǎodào (find)|
|Tīng (listen)||+ dào =||Tīngdào (hear)|
|Mǎi (shop)||+ dào =||Mǎidào (buy)|
How does this make it easier to learn? Because it reduces the number of words you need to learn, and, to a lesser extent, reduces ambiguity.
If you look at the Result column in the table you will see that English words are completely different. Where as, in Chinese, you just add a compliment of result. There are not many complement-of-result words, such as dào, jiàn, wǎn, huì, and hǎo.
Yang yang does a great job of explaining these concepts so watch the video to learn more.