0 any gas in a group that contains carbon and hydrogen atoms, with the carbon atoms joined together in a double bond: --
Ethene and propene are alkenes.
1 any of a group of substances that contain only the elements carbon and hydrogen, which are held together by a chemical bond in which two atoms share two pairs of electrons --
We can complete it step by step however long the road is and it can't be completed however short the road is if you don't even mark your footprint.
Можем да го завършим стъпка по стъпка, колкото и дълъг да е пътят и не може да бъде завършен, колкото и кратък да е пътят, ако дори не маркирате отпечатъка си.