下列哪一项是办公室内常见的传染病
A.呼吸道传染病
B.皮肤及食道传染病
C.心脏病及精神病
参考答案：A
在等差数列{an}中，前n项和为Sn，且S2011=-2011，a1007=3，则S2012等于（ ）
A．2012
B．-2012
C．1006
D．-1006
-----Is this city _______ he visited the other day?
------No, this is the city ________ he was born.
A, that , ,that B. the one, where C. the one, on which D. that , where
