Afocal arrangement that has a secondary mirror that reflects the focused light back through a hole in the primary mirror is a
a. cassegrain focus
b. newtonian focus
c. schmidt-cassegrain focus
d. schmidt focus

clinically, some people often have repeated allergies, eczema and respiratory infections or other parts of the infection, in this case, in addition to some routine tests such as tests for white blood cells, immunoglobulin series, lymphocyte subsets, etc., the five immune immunoglobulin tests are also necessary.

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explanation:

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