a virulent strain of flu的用法和样例：
- But she would like to start a conversation about why the United States seems particularly vulnerable to such a virulent strain of anti-intellectualism.
- In Belgium and the Netherlands, a virulent new strain of avian flu was wiping out entire chicken farms.
- She's still recovering from a bout of flu.
- This strain of wheat can grow during a cold spring.
- There's a lot of flu going round at the moment.