They have________signs in some places to remind (提醒)the visitors not to step on the grass.
My uncle's house in the downtown area is much smaller than ours, but it is twice __________ expensive.
John found it a challenge to meet the needs of the boss. __________, he had no way to satisfy him.
What made me surprised was his attitude __________ the mistakes I had made.
What's your attitude __________ that problem?
—Mike, you don't seem to be quite __________ today. —Well, I hardly slept last night. I was preparing for a report.