已知Ag₂SO₄的Ksp为2.0×10^-5，将适量Ag₂SO₄固体溶于100 mL水中至刚好饱和，该过程中Ag⁺和SO₄^2-浓度随时间变化关系如图[饱和Ag₂SO₄溶液中c(Ag⁺)＝0.034 mol·L^-1]。若t1时刻在上述体系中加入100 mL 0.020 mol·L^-1 Na₂SO₄溶液，下列示意图中，能正确表示t1时刻后Ag⁺和SO₄^2-浓度随时间变化关系的是

A.

B.

C.

D.

The service life of distress signals must be not more than（）.

A.forty two months from the date of manufacture

B.thirty six months from the date of the last inspection

C.twenty four months from the date of approval

D.twelve months from the date of purchase