受精后的鸡蛋，自然状态下不经孵化则不会变成小鸡，其制约因素是（　　）

交往是一门艺术，它需要平等尊重去培育，宽容友善去浇灌，诚实守信去护理。（  ）

Dear Sir or Madam.

    One of the teachers at my school in New York tells me that your school has summer course. I am planning to go to Beijing next summer and would like to take a short one-month course.

    I am 18 years old and have been studying Chinese for six years. I was born in the USA and have never been to China before. I am going to study Chinese at the university. I think the course will help me improve my Chinese.

    Could you send me a catalogue(目录) and application form (申请表)? I would also like information about Beijing and other places nearby. I hope to do some travelling when the course is over.

    Thank you! I am looking forward to your reply

Very truly yours,

Jim Green

已知Ag₂SO₄的K_sp=c²（Ag⁺）×c（SO₄^2﹣）=1.4×10^﹣5，将适量Ag₂SO₄固体溶于100mL水中至刚好饱和，饱和Ag₂SO₄溶液中c（Ag⁺）=0.032mol•L^﹣1．若t₁时刻在上述体系中加入100mL相应溶液，下列示意图中，不能正确表示t₁时刻后Ag⁺和SO₄^2﹣浓度随时间变化关系的是（   ）