找出下列复合句中的宾语从句，并分析其构成： Millie knows that it’s important to finish homework on time. Millie often doubts whether/if it is worth spending so much time on homework. 3. Millie doesn’t know how she should deal with her problem. 4. Simon doesn’t understand why his parents are so strict with him. 5. I wonder how I can achieve a balance between my schoolwork and my hobbies.