—Oh, it's so cold. We haven't had such a severe winter for so long, _______ we？

—Yes, the forecast says it's going to get worse _______ it warms up.

A．have; before

B．had; after

C．did; when

D．do; if

教师要想满足学生发展需要，拓宽知识视野，更新知识结构，不断提高专业素养和教育教学水平，就必须()

A．爱岗敬业

B．勇于创新

C．严谨治学

D．终身学习