前瞻性调查是预先设计暴露组与未暴露组，观察其反应，最后对两组结果作分析，是"从因到果"的方法。
参考答案：对
The problem of the polluted river _____ right away to prevent possible danger to the local people.[ ]
A. should be solved
B. should have been solved
C. may be solved
D. might have been solved
MDEA配方溶液中的“配方”没有加剧MDEA溶液腐蚀的组分。
