1. The situation today is obviously quite different from ________ it was only 50 years ago.
A) what B) which
C) when D) such
2. Most doctors recognize that medicine is ________.
A) an art as much it is a science
B) as much an art as it is a science
C) as an art as much it is science
D) much an art as it is a science
3. ________ the punishment was unjust, Helen accepted it without complaint.
A) However B) So long as
C) Even though D) Since
4. The time has come ________ we can make extensive use of nuclear energy.
A) when B) while
C) as D) since
5.Some metals are better conductors of electricity than others , _____ means that the former have atom that contain more free electron than the latter.
A) that B) this
C) which D) it
6. There is hardly a environment on earth ________ some species of animal or other has not adapted to an environment successfully.
A) to which B) wherever
C) so that D) as to
答案：1.A 2.B 3.C 4.A 5.C 6.A