a smoke screen的用法和样例：
- They hide their real intentions behind a smoke screen of religious piety.
- But Baidu's crusade fire was so fierce and concentrated, besieged on all sides amid the calm Li Hui in an attempt to open a smoke screen after another to find out the real "enemy.
- Sam's been telling everybody his wife is having an affair.But we think this is nothing but a smoke screen for his plan to divorce her for a younger woman and save paying her a lot of alimony.
- They stopped work to have a smoke.
- I'll have a smoke if you don't mind.