动点(x，y)的轨迹是圆。
(1)|x-1|+|y|＝4
(2)3(x2+y2)+6x-9y+1＝0
A. 条件(1)充分，但条件(2)不充分。
B. 条件(2)充分，但条件(1)不充分。
C. 条件(1)和(2)单独都不充分，但条件(1)和条件(2)联合起来充分。
D. 条件(1)充分，条件(2)也充分。
E. 条件(1)和(2)单独都不充分，条件(1)和条件(2)联合起来也不充分。
查看答案
What is the biggest shock in the writer's career？
A. She lost her job as a field systems analyst in 1920s.
B. She lost her grandmother who was her inspiration.
C. She was denied the post of first manager on account of sexual discrimination.
D. She quit after being totally blown away and crawled back home.
图中所示结构1杆轴力为()。
A. 拉力
B. 压力
C. 0
D. Fp
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