If a halogen, such as bromine, is added in the place of hydrogen, the reaction is called halogenation.

如果加入素，如溴，代替氢，则该反应。

You also learned a little bit about cis-trans isomerism and learned a few important reactions of alkenes and alkynes such as hydrogenation, halogenation, and polymerization.

还了解了一些顺反异构现象，并了解了烯烃和炔烃的一些重要反应，例如氢、和聚合。