a smoke screen的用法和样例：
- They hide their real intentions behind a smoke screen of religious piety.
- Lighting fires to create a smoke screen is an ancient ruse in military tactics.
- 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.