A complex sentences has an independent clause and at least one dependent clause. Here is 5 comlex sentences examples;
1.When he handed in his homework, he forgot to hand the teacher the last stage.
2.The human brain never stops working until you stand up to speak in public.
3.Even though she suffered from arthritis, she studied hard because she wanted to go to medical school in London.
4.Because Alex and Michael arrived at the bus station before noon, I did not see them at the station.
5.Before the bell rang, the children packed up, and the teacher collected their work.