1. The sky is blue. (The sky = subject, is = linking verb, blue = subject complement)
2. She seems happy. (She = subject, seems = linking verb, happy = subject complement)
3. This cake tastes delicious. (This cake = subject, tastes = linking verb, delicious = subject complement)
4. He became a doctor. (He = subject, became = linking verb, a doctor = subject complement)
5. The movie was quite boring. (The movie = subject, was = linking verb, quite boring = subject complement)
Let me know if you would like more examples!