简述PAGE的分离原理。

圆度误差用一般的量具很难测量准确，必须使用圆度仪来测量。( )

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.

Faugel’s research showed that beta blockers given to his sample________.

A．increased scores less than the national average

B．increased scores the same as the national average

C．decreased scores

D．increased scores much more than the national average

“此中有真意，欲辨已忘言”中的“真意”指的是什么？

肺灌注显像的原理是以下哪一种机制（）

A.细胞选择性摄取

B.化学吸附作用

C.微血管栓塞

D.特异性结合

E.非特异性结合