______ without friends ______ the most difficult challenge for Chuck while living on the island.
—Do you still remember the accident? —Yes. Actually, I have experienced nothing more __________.
Do you wake up every morning __________ energetic and ready to start a new day?
—I wish I __________ the meeting. —But you didn't.
The doctor telephoned to say that he couldn't __________ the meeting because he had to look after a patient.
More highways have been built in China, __________ it much easier for people to travel from one place to another.