题干
The president took immediate steps ________ the improvement of the poor’s living conditions.
A：contributed to
B：contribute to
C：contributing to
D：be contributed to
答案(点此获取答案解析）
C
）与丙烯的共聚物是一种高分子阻燃剂，具有低毒、热稳定性好等优点．完成下列填空：
