Shanghai lies _______ the east of China and _______ the northeast of Guangdong.
A:in; to
B:in; in
C:to; to
D:to; in
以下国家位于西亚,但不属于中东的是
已知数列{an}满足a1=3,an-an+1+1=0n∈N*则此数列中a10等于( )