21. _____ is used occasionally to give children transient protection against measles, or hepatitis A. A: Human gamma globulin B: Gamma-G globulin C: Serum derived from immunized horses D: Plasma from immunized individuals

Infants are particularly subjected to infectious diseases; that is<br/>why they have to be ______. A: imitated B: disarmed C: immunized D: bumped

A magazine is best for... A: Statistics on the number of children immunized against diseases in the United States. B: Detailed literary analysis. C: Information about current social trends.

Several children in a kindergarten class have been treated for pinworm. To prevent the spread of pinworm, the school nurse meets with the parents and explains that they should（） A: tell the children not to bite their fingernails. B: not let children share hairbrushes. C: tell the children to cover their mouths and noses when they cough or sneeze. D: have their children immunized.

Compared with normal mice, mice immunized with antigens for many times have the larger and heavier spleens because of ( ). A: proliferation of antigen specific T cells B: proliferation of antigen specific B cells C: proliferation of antigen specific T and B cells D: proliferation of antigen non-specific T and B cells