1. Apple was struggling; IBM continued to grow.

2. The original sentence is correct.

3. Three thousand students applied; twelve hundred were turned away.

4. Some doctors inform their patients; others keep them in the dark.

5. Doctors are wary of miracle drugs; they may have side effects.

6. Metanoia is out of the question; he sees no need for a spiritual conversion.

7. The lover feels that, for the moment at least, that she is his; he notices his heart swelling with joyful surprise.

8. The parking problem is not a problem; it is a disaster.

9.  The original sentence is correct.

10.  Students no longer park there; they park in the garage.

11. The original sentence is correct.