What would happen to the earth if the sun suddenly switch off some day?
It is widely believed that an apple which fell from its branches were the _______ for Newton’s discovery of gravity.
Raising _______ retirement age in progressive steps is in _____ line with China’s labor market realities and should be prioritized, an official said Tuesday.
It was not until 1911, _______ the first vitamin was identified, _______ people realized the importance of it.
We should think carefully about ______ Mr. Needham said at the meeting.
Have you ever met with this case in your life you can't understand others even if they have said something several times?