Step 1: Identifying the type of sentence.
We are given two simple sentences, and we need to combine them into a complex sentence. A complex sentence consists of an independent clause and a dependent clause.
Step 2: Analyzing the sentence.
The second sentence explains why teachers command respect. We can use "because" to join the two ideas into a complex sentence.
Step 3: Combining the sentences.
Some teachers command respect because they are good.
Final Answer: \[ \boxed{\text{Some teachers command respect because they are good.}} \]