正常人尿渗透压一般多在下列哪项范围内（）

A.280～320Osm/kgH₂O

B.320～400Osm/kgH₂O

C.280～500Osm/kgH₂O

D.600～1000Osm/kgH₂O

E.1000～2000Osm/kgH₂O

I am honored to be here today, (1) Harvard at this celebration of the College Board’s half century of working to promote (2) and equal opportunity in higher education.
Before I say anything else, I want to thank everyone in the room for the work you do every day to make college (3) , available, and (4) for millions of young people across the country.
I want to focus my remarks on a matter of (5) to American familiesand to the future of the nation -- restoring education to its proper role as a (6) to equal opportunity and (7) in our society.
This has been an (8) in higher education, with great and creative efforts made by many institutions. Earlier this year, we announced a new (9) at Harvard aimed at the students from families of low and (10) income. Under our new program, families with incomes of (11) will no longer be expected to contribute to the cost of attending Harvard for their children. Families with incomes of less than $ 60,000 will also see their (12) reduced.
We are proud of this effort at Harvard, but we are aware that the programs of individual institutions with means can never be a substitute for our shared (13) to provide adequate funding for Pell grants and other financial aid, and for the state and community college systems that make higher education (14) and affordable for the (15) .
There is something empty about (16) initiatives that may be right for one institution without attention to their broader impact. (17) , we (18) if we urge changes in national policy without doing what we can on our own campuses.
In this spirit, I want to (19) today a problem that is emerging with (20) in this nation.