21. He’s got himself into a dangerous situation _____ he is likely to lose control over the plane.
A. where B. which
C. while D. why
22. He made another wonderful discovery, ______ of great importance to science.
A. which I think is B. which I think it is
C. which I think it D. I think is
23. Dorothy was always speaking highly of her role in the play, ____, of course, made the others unhappy.
A. who B. which
C. this D. what
24. Their problem today is somewhat similar to _____ they faced many years ago.
A. that B. which
C. that which D. it
25. I saw some trees the leaves of _____ were black with disease.
A. that B. which
C. it D. what
26. The famous basketballer, _______ tried to make a comeback, attracted a lot of attention.
A. where B. when
C. which D. who
27. When they went into the shop and asked to look at the engagement rings, the girl brought out a cheaper one, _______ she had arranged with James.
A. the which was what B. what was that
C. which was what D. that was that