妈妈！爸爸！这是我的朋友，Sarah Miller

___Mum! ___Dad! This is my friend, Sarah Miller.

我妈妈做的苹果派是世界上最好吃的。

My ___mum makes the best apple pie in the world.

关于考试答案，老师要求我们保持沉默。

The teacher asked us to keep ___mum about the exam answers.