单项选择题
We've done once but failed. We'll have to do it（）time.
A. a second B. the second C. the twice D. twice
单项选择题 The door was （） and I could not see who she was talking to
单项选择题 Can you remember all the （）for our school
单项选择题 He was a good swimmer, so he （）swim to the river bank when the boat sank.
