—You look unhappy, my son?—I’m wondering how long it’ll be we come to China again.
They arrived at a farmhouse,in front of ________ sat a small boy.
The pen ________ he is writing is mine.
Can you lend me the book ________ the other day?
At the party,John made up a joke,________ people burst out laughing.
That is the day ________ I'll never forget.