25. Cars do cause people some health problems, in fact far more serious _____ than computers do.
A. one B. ones C. it D. those
26. It is known to all that the US is about the same size as China, but its population is five times _____.
A. as few B. fewer C. as little D. smaller
27. Some doctors want to examine the impact those marine mammals have _____ the children who had tried dolphin-assisted therapy.
A. on B. with C. to D. about
