Up to now, our society ________ with limited living space and a shortage of natural resources.
A．has been challenged B．is being challenged
C．is challenging D．has challenged
—Will you see me off at the airport at ten tomorrow morning?
—Sorry, I ________ a lecture then.
A．will be giving B．will give
C．give D．have given
—The rain ________ fast and heavy.
—You should ________ some shelter. Look at you—you are all wet.
A．is coming; find B．comes; have found
C．came; find D．came; have found
I had wanted to help you last night but I couldn't spare any time, for I ________ a composition which I have to hand in this morning.
A．wrote B．was writing
C．had written D．have written
—How is your cousin, Kate?
—She broke her leg and ________ medical treatment since.
A．is receiving B．has received
C．received D．has been receiving
—Lucy, tell me about your trip to the beach.
—Awful! There ________ too many holidaymakers.
A．had been B．were
C．would be D．have been
