单项选择题
未知题型 有关淋巴显像剂要求的描述,哪些是正确的 A.最佳显像剂颗粒直径应大于4~5nm,小于25nm B.99mTc-硫化锑胶体颗粒大小适宜,在体内比较稳定 C.99mTc-右旋糖酐颗粒小,在淋巴系统内移行速度较快,适合动态显像 D.选择同时被毛细血管吸收的显像剂,不影响淋巴显像的质量 E.不能透过毛细血管基底膜的显像剂都可以进行淋巴显像
单项选择题 下列叙述中属于造成目前世界粮食问题的原因是( )
单项选择题 The art of war has undergone such changes that _______.A.we no longer use any French words of the Middle AgesB.many words once common are not used any longer and they are replaced by Italian wordsC.French military terms have disappeared from the English languageD.many words once common are now only in historical use and their places have been taken by the newly-borrowed words