核医学影像与其他影像比较（）

A.可以反映密度的变化

B.可以反映回声的改变

C.可以反映氢核密度的变化

D.可以反映代谢、血流和功能改变

E.空间分辨率更高

Mr. Faugel was convinced that student nervousness had affected their scores; to reduce the anxiety of these students who had already been tested, he gave 22 of them a beta blocker before readministration of the test. Their scores improved significantly. The other 8 students (who did not receive the beta blockers) improved only slightly. Second-time test-takers nationwide had average improvements which were similar to those in Faugel’’s non-beta blocker group. Beta blockers are prescription drugs which have been around for 25 years. These medications, which interfere with the effects of adrenalin, have been used for heart conditions and for minor stress such as stage fright. Now they are used for test anxiety. These drugs seem to help test-takers who have low scores because of test fright, but not those who do not know the material. Since there can be side effects from these beta blockers, physicians are not ready to prescribe them routinely for all test-takers.

Re-administration in this passage refers to giving________.

A．the test again to people without administering beta blockers

B．the test again to both groups after beta blockers have been administered to one group

C．the test to both groups of test-takers and then giving them beta blockers

D．the beta blockers without retesting