The theory of relativity ______ by Einstein, who was a famous physicist. A. was developed B. is developed C. develops D. developed

“Could you turn off the stove? The potatoes ______ for at least thirty minutes.” A. boiled B. were boiling C. are boiling D. have been boiling

“What _______ if the earth stopped moving?” A. happened B. would happen C. happens D. will happen

I _______ with my aunt when I am on holiday in Ho Chi Minh City next month. A. will have been staying B. will have stayed C. stay D. will be staying

I _______ work last week, but I changed my mind.
A. have started B. was going to start C. had started D. would start

Due to ever more spreading poaching, there _______ a dramatic decline in the number of elephants over the last decade. A. was B. is C. has been D. had been

The boat was sailing north when a terrible storm _______. A. had broken B. broke C. would break D. was breaking

The packages _______ so that it would be easier to carry them. A. are tied in a bundle B. are tied altogether C. were tied in a knot D. were tied together

Only one of our gifted students _______ to participate in the final competition. A. has been chosen B. have been chosen C. were choosing D. chosen

If it _______ for the heavy storm, the accident would not have happened. A. isn’t B. hadn’t been C. were D. weren’t