用所给单词填空 This was ______ he didn't come. The question is ______ you should do next. The problem is ______ would go there. What shall we do ______ it rains this afternoon. I was very thirsty , ______ I drank all the water. They didn't take a seat ______ their teacher sat down. Peter was working ______ Jone was singing. Work hard , _____ you will fail. Knock at the door ______ you come in. I wonder ______ my brother can pass the exam or not.