مساعدة هامة قبل الامتحان

Hello there
A simple sentence is a sentence that includes one verb and one idea in the sentence, such as :
Ahmed goes to school everyday.
Jane speaks four languages
On the other hand, the compound sentence is a sentence that includes two ideas ut they are joined by one connector such as:
Alex went to school and met her friends.
Here as you see "Alex" did two things: going to school and meeting her friends. The two ideas are connected by "and" but they are still two separate ideas. Other connectors that can function here are but, so, therefore, however,additionally…etc.
The third type of sentences you asked about is the complex sentence. This type of sentence is a little different. It consists mainly of two sentences with two different ideas and one connector but they can not be separate like the compound sentence.By this i mean that the meaning of the one sentence is incomplete if it is separated from the other main one. For example:
After they watched the movie, they had their dinner.
When he saw his father, he got shocked.
Here you notice that there are two sentences, but the first sentence after the connector (after and when) can not complete the meaning. They need the main sentence after the comma to complete the meaning. there are other connectors that can be used here such as before, while, because, if and although. You can refer to Unit one grammar in grade 12 On Location book for more useful details and examples. I hope you find this useful. Thank you.