It was not until this year _____ scientists managed to make a cat and a goldfish disappear from sight using an invisibility cloak(斗篷)

His father told me that he __________ for the United States three days __________

Dad, I have been appointed as manager of our company, but I’m worried about it.—Why worry Increased responsibility can often ______ your best qualities.

Neither my sister nor I been to America before.

I ______ for Shanghai this Saturday, so I want to know when the earliest plane ______