单项选择题
Only ______ making investigations ______ have the right to speak.
单项选择题 Thinking that you know ______ in fact you don"t is not a good idea.
单项选择题 Mrs. White became a teacher in 1985. She ______ for twenty years by next summer.
单项选择题 Was it in 1969 ______ the American astronaut succeed ______ landing on the moon
