certainly
ad.必定，一定;当然，行
I certainly never expected to become a writer.我当然从未期望自己成为一名作家。
certainty
n.必然的事，确定的事实;确信，确实
The result is impossible to predict with any degree of certainty .无法有把握地去计算结果。
certificate
n.证(明)书，执照
a degree certificate学位证书
certify
vt.证明，证实;发证书(或执照)给
The accounts were certified by an auditor.这些账目经审计员核实过。
decline
n.下降 vi.下降;衰退;谢绝
vt.谢绝
the economic decline faced by many cities许多城市面临的经济衰退
