-Did Jack come back early last night? -Yes. It was not yet eight o'clock _____ he arrived home.
_______ basic first-aid techniques will help you respond quickly to emergencies.
People develop _______ preference for a particular style of learning at _______ early age and these preferences affect learning.
—Is the chemistry experiment easy? —______. I’ll just do my best.
The number 5.12 is a special number,__ ,I think, that will be remembered by Chinese people forever.
The country has already sent up three unmanned spacecraft, the most recent__at the end of last March.