Question

building compound-complex sentences to add meaning
have you ever thought about traveling to another country? pick a place that interests you, and where your native language is not spoken. once you have picked a place, you can research language - learning options. you can use online programs or find a class. you could learn and practice with a friend, and then take a dream vacation. learning a language can be difficult. it is one of the the most useful hobbies. ive tried it.
what compound - complex sentence can be formed from the underlined section of the passage?
learning a language can be a difficult and useful hobby; ive tried it.
learning a language can be difficult; it is one of the most useful hobbies ive tried.
learning a language can be difficult, it is one of the most useful hobbies ive tried.
learning a language can be difficult, yet it is one of the most useful hobbies that ive tried.

Explanation:

A compound - complex sentence has at least two independent clauses and one dependent clause. The first two options are compound sentences (two independent clauses joined by a semicolon). The third option is a run - on sentence. The fourth option "Learning a language can be difficult, yet it is one of the most useful hobbies that I've tried" is a compound - complex sentence with the independent clauses "Learning a language can be difficult" and "it is one of the most useful hobbies" joined by the coordinating conjunction "yet", and "that I've tried" is a dependent clause modifying "hobbies".

Answer:

Learning a language can be difficult, yet it is one of the most useful hobbies that I've tried.