Question

Which sentences are compound-complex sentences? Check all that apply.

Your brain produces more dopamine when it is engaged in solving a puzzle.
Our brains produce a chemical known as dopamine that is involved in learning and in creating memories.
We can put together a puzzle that has challenging shapes, or we can try to solve the sudoku in the newspaper.
Working on puzzles increases our concentration and can expand our creativity; puzzle-making even has health benefits.
Students can improve their performance when they are faced with a challenging task, but they will have to start doing jigsaw puzzles.

Answer 1

Compound-complex sentences: 3 and 5.

Brief breakdown:
- 3: "We can put together a puzzle that has challenging shapes, or we can try to solve the sudoku in the newspaper."
- Independent clauses: "We can put together a puzzle..." and "we can try to solve the sudoku..."
- Dependent clause: "that has challenging shapes" (relative clause)

- 5: "Students can improve their performance when they are faced with a challenging task, but they will have to start doing jigsaw puzzles."
- Independent clauses: "Students can improve their performance..." and "they will have to start doing jigsaw puzzles."
- Dependent clause: "when they are faced with a challenging task" (adverbial clause)

Why the others are not:
- 1 and 2 are complex (one independent + one dependent).
- 4 is compound (two independents) but has no dependent clause.