These diagrams are especially helpful when we have a concrete problem ________ at hand.
A．be solvedB．to solve
C．solvedD．being solved
At last, we found ourselves at the foot of a hill with trees providing shade and ________ down to eat our picnic lunch.
A.sittingB．having sat
C．to sitD．sat
Launched in March 2010, China Face has been a daily news feature ________ on a Chinese individual.
A.being focusedB．focusing
C．to be focusedD．to focus
We entered the café and sat down by the window, waiting ________.
A．to serve B．to be served
C．serving D．served
With so many exercises ________， the students are having a hard time.
A．finished B．finishing
C．to finish D．being finishing
Whom do you expect to have ________ the baggage to the airport?
A．deliver B．to deliver
C．delivered D．delivering
