1、It was hard to keep a straight face while I answered their questions.
回答他們的問題時，真叫我忍俊不禁。

2、It was hard to keep a straight face while I answered their questions
回答他們的問題時，真叫我忍俊不禁。

3、It was difficult to keep a straight face when he fell over the dog
當他絆著狗摔了一跤時，大家很難扳著臉不笑。

4、We often keep a straight face or use an unsmiling expression when we're making a joke.
當我們開玩笑的時候，我們經(jīng)常繃著臉或使用不笑的表情。

5、It was difficult to keep a straight face when he fell over the dog.
當他絆著狗摔了一跤時，大家很難扳著臉不笑。

keep a straight face翻譯