The subordinate clause in the sentence "The trouble was that he forgot where he put his keys" is a noun clause.
<span>A subordinate clause is a clause that is dependent on the main clause. It cannot stand alone. The subordinate clause in this sentence is: "The trouble was that". The main clause in this sentence is: "he forgot where he put his keys". From the above we can see that the main clause can stand on its own but the subordinate clause cannot stand on its own. </span>
Answer: The sentences are: When you experience a new place, it enhances your understanding of other people.;
After traveling to a national park, people feel a greater appreciation for nature.;
You should travel somwhere you have never been because you can explore a new place.
Explanation: Complex sentence is when a sentence has one independent clause, which is the main clause and one or more dependent clause. One independent clause or main clause means that the sentence can stand by itself.
Subordinating conjunctions are often used to link the sentences, normally a dependent sentence to an independent one. Their function, in conjunction with the dependent sentence, is to stabilish a place, a reason, a time, a concession or a comparison. The most common conjunctions are if, when, although, because, before, even though and until.