—Why do you look sad?
—There are so many problems ________.
A．remaining to settle B．remained settling
C．remaining to be settled D．remained to be settled
________ as the “first lady of speech”，Dr, Lillian Glass is recognized as one of the world's leading experts on communication skills.
A．Knowing B．Having known
C．Known D．To be known
John received an invitation to dinner，and with his work ________，he gladly accepted it.
A．finished B．finishing
C．having finished D．was finished
—Come on，please give me some ideas about the project.
—Sorry.With so much work ________ my mind，I almost break down.
A．filled B．filling C．to fill D．being filled
The children went home from the grammar school，their lessons ________ for the day.
A．finishing B．finished
C．had finished D．were finished
The country has already sent up three unmanned spacecraft，the most recent ________ at the end of last March.
A．has been launched B．having been launched
C．being launched D．to be launched
