根据句子意思填单词。

1. We have a Chorus c_______ each year.

2. The last day of April is April the t_______.

3. —Do you have a pop c_______?

    —Sorry, I don't know.

4. September is the n_______ month of the year.

5. There is a speech c_______ between Class 4 and Class 5.

污染土壤修复效果评定的概念？污染土壤修复效果评定是土壤修复环境工程必不可少的重要环节。污染土壤修复效果的评定就是结合有效的化学分析手段，通过对土壤生态系统中不同物种生物组分损伤的观察，定性或定量预测修复后土壤中污染物对土壤生态系统和人类健康产生有害影响的可能性。