With some technical problems to be solved, it may be a while _______ the system is put into use.
The “Chinese Dream” is _______ dream to improve people’s well-being and ____ dream of harmony, peace and development.
--- Did you remember to give Mary the money you owed her? --- Yes.I gave it to her _____ I saw her.
The president promised to keep all the board members _____ of how the negotiations were going on.
______ chemistry is a branch of chemistry.
More and more high-rise buildings have been built in big cities ______ space.