Einstein’s theory of relativity seemed hard to believe at the time _______.

单项选择题Sometimes it is necessary to be careful _______ the right date to sit for a test.

单项选择题Tina’s children, _____ all live nearby, organized a big party for her eightieth birthday.

单项选择题When Sally ______ the criminal ______ her house, she screamed at the top of her voice because she didn’t want ______.

单项选择题Lest anyone _____ it strange, let me assure you that it is quite true.

单项选择题Our planned visit to the United States _______ because we were unable to get the visas.