31. --- My son is lost. Did you
see a boy pass by here?
--- I saw
______ boy hidden behind ______ tree over there. You may go and have a look.
A. a;
the B. 不填;the C. a; 不填 D. a; a
32. Greenhouse phenomena would cause ______ rise in sea levels worldwide and
change ______ weather on the earth.
A. a;
the B. the; 不填
C. a; 不填 D. 不填; the